17th Patras Workshop on Axions, WIMPs and WISPs

8 Aug 2022, 09:00 → 12 Aug 2022, 18:00 Europe/Berlin

Alte Mensa

The nature and composition of Dark Matter and Dark Energy are two of the most pressing mysteries particle physics and research in these fields is presently gathering increasing momentum and attracting the efforts of scientists from many international institutions. The "17th Patras Workshop on Axions WIMPs and WISPs” is the latest event in an annual series of conferences, started in 2005 at CERN. This workshop is aiming to continue the rich and successful series, reviewing recent theoretical advances, laboratory experiments, novel ideas as well as astrophysical and cosmological results in the fields of axions, WIMPs and WISPs. Participation by young scientists is strongly encouraged.

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Our sponsors:

Monday 8 August

09:00 → 09:20 Organizers

Convener: Dmitry Budker

09:00 Welcome and announcements

Speaker: Arne Wickenbrock

09:04 Welcome from JGU Mainz

Speaker: Stefan Müller-Stach

09:12 Welcome from PRISMA+ Cluster of Excellence

Speaker: Matthias Neubert

09:20 → 10:00 Invited talk

Convener: Dmitry Budker

09:20 WIMPs

WIMPs plenary

Speaker: Kimberly Palladino

Palladino WIMPs PATRAS.pdf

10:00 → 10:40 Contributed talks: I

Convener: Dmitry Budker

10:00 Preliminary results for DFSZ axion definitive searches at IBS-CAPP

The CAPP-12TB experiment is a microwave cavity search for dark matter axions at IBS-CAPP in KAIST. The system consists of a superconducting solenoid with a bore size of 320 mm and a maximum field of 12 T at the magnet center, a cryogenic dilution fridge with physical temperatures around 30 mK with the cavity load, and a nearly quantum-limited noise Josephson parametric amplifier. The copper cavity has a large volume (37 L) and an unloaded Q-factor around 100,000 along its frequency range tuned by a copper rod. We report the first preliminary results of the experiment which excludes the Dine-Fischler-Srednicki-Zhitnitskii (DFSZ) axion model for the mass range 4.51 μeV (1.09 GHz) to 4.59 μeV (1.11 GHz) at a 90% confidence level. The CAPP-12TB experiment will continue its search for DFSZ axions over a wider range of axion masses.

Speaker: Mr Andrew Kunwoo Yi (KAIST, IBS-CAPP)

PATRAS2022_CAPP12TB_COMP.pdf

10:20 Hunting for axions and axion-like particles with the nEDM and n2EDM experiments at PSI

Ultralight Axions and axion-like particles are important dark matter candidates. If they are responsible for a significant proportion of dark matter, and are thus present in a large number density, they can be viewed as a galactic-scale classical field oscillating at a frequency proportional to their mass m$_a$. Interactions of a coherently oscillating axion dark matter field with gluons could then induce an oscillation in the neutron EDM. By using data from the nEDM experiment at the Paul Scherrer Institut this allows us to set laboratory constraints on the axion-gluon coupling.

We present a refined analysis of the data from the nEDM experiment at PSI which improves the limits on the oscillation amplitude, and thus coupling strength, by a factor of two for mass ranges between 10$^{-24}$ eV ≤ m$_a$ ≤ 10$^{-17}$ eV (corresponding to frequencies between 2·10$^{−8}$ Hz - 5·10$^{−5}$ Hz) compared to our previously published results. Furthermore, we will discuss progress and prospects in complementary (co-)magnetometry experiments and searches for axion-mediatied fifth-force effects in the same apparatus. Finally, we give predictions on the exclusion limits that will be achieveable with the data from the n2EDM experiment at PSI, which is expected to start data-taking in 2023.

Speakers: Nathalie Ziehl (ETH Zürich), on behalf of the n2EDM collaboration

patras22.pdf

10:40 → 11:10 Coffee

Coffee will be served at ....

11:10 → 12:30 Contributed talks: II

Convener: Le Hoang Nguyen (Hamburg Universität)

11:10 Status of the FASER Experiment at the LHC

The FASER experiment is a new small and inexpensive experiment that is located 480 meters downstream of the ATLAS experiment at the CERN LHC. FASER is designed to discover dark photons, ALPs, and other light and very weakly-interacting particles that are produced in the far-forward region, outside of the ATLAS detector acceptance. The experiment has been successfully constructed and installed is taking data during Run-3 of the LHC. This talk will present the physics prospects, detector design, commissioning status as well as first recorded data of FASER.

Speaker: Matthias Schott

FASER_PATRAS2022_SCHOTT.pdf

11:30 Proposals for searches of scalar field dark matter using cavity resonators

We consider scalar field dark matter model with a dilaton-like coupling to electromagnetic field. If the mass of this scalar field falls into the range of hundreds of MHz, it may be detected using cavity resonator techniques similar to those used in the search of the axion dark matter in the ADMX and ORGAN experiments. However, we show that the cavity resonators in these experiments have low sensitivity to the scalar-photon coupling. We propose new cavity resonators with various configurations of electric and magnetic fields that may have a significant sensitivity to the scalar field dark matter. Such resonators may be considered for new dark matter searching experiments in future.

Speakers: Igor Samsonov (University of New South Wales), Victor Flambaum (University of New South Wales, School of Physics, Sydney 2052, Australia)

Talk-scalar.pdf

Talk-scalar.pptx

11:50 WISPLC: Search for Dark Matter with LC Circuit

The focus on dark matter search has expanded to include low-mass particles such as axions or axion-like particles (ALPs), and novel theoretical schemes extending the phenomenological landscape, within QCD and beyond, also garnered additional interest in recent decades. Assuming dark matter is composed of axions, in presence of a strong magnetic field, they induce a displacement current that generates a magnetic field detectable by state-of-art superconducting quantum interference device (SQUID). The Weakly Interacting Slender Particle detection with LC circuit (WISPLC) is a precision direct detection experiment that will search for light dark matter candidates such as ALPs in parts of the parameter space previously unexplored. The key facility is a large-scale cryogen-free magnet system that can produce a maximum solenoidal magnetic field of 14 Tesla at the center of the bore, inducing an axion-sourced toroidal magnetic field which can be captured by a pickup loop. We present two detection scheme: a broadband detection with up to 2 MHz bandwidth, and a resonant scheme where a LC circuit is used to enhance the signal with an expected Q factor $\sim 10^4$. Taking into account the irreducible intrinsic flux noise of the detector, we estimate the sensitivity of the experiment in the axion mass range between $10^{-11}$~eV and $10^{-6}$ eV to reach a detectable axion-photon coupling of $g_{a\gamma\gamma}\approx 10^{-15}~\mathrm{GeV}^{-1}$, making it possible to probe mass ranges corresponding to ultralight axions motivated by string theory.

Speakers: Zhongyue Zhang (Institut für Experimentalphysik, Universität Hamburg), Oindrila Ghosh (II. Institute for Theoretical Physics, University of Hamburg)

Zhang_Ghosh_WISPLC.pdf

12:10 Supax - A new superconducting axion search experiment @ Mainz

Axions, the famous hypothetical particle that explains the absence of CP violation in QCD is also an exciting candidate for dark matter.
At Mainz we're currently constructing a new experiment utilizing superconducting RF cavities in a 14T magnetic field to search for axions in the $8.4\,\textrm{GHz}$ range. In this talk the physics reach of the experiment will be discussed as well as the status and first test-results of our prototype cavity.

Speaker: Kristof Schmieden (JGU Mainz)

Suapx_Schmieden.pdf

12:30 → 14:00 Lunch

Lunch, Food available at ....

14:00 → 14:30 Long talk: Session 1

Convener: Gulden Othman (University of Hamburg)

14:00 The Piezoaxionic Effect

Axion dark matter (DM) constitutes an oscillating background that violates parity and time-reversal symmetries. Inside piezoelectric crystals, where parity is broken spontaneously, this axion background can result in a mechanical stress. We call this new phenomenon "the piezoaxionic effect". When the frequency of axion DM matches the natural frequency of a bulk acoustic normal mode of the piezoelectric crystal, the piezoaxionic effect is resonantly enhanced and can be read out electrically via the piezoelectric effect. We also point out another, subdominant phenomenon present in all dielectrics, namely the "electroaxionic effect". An axion background can produce an electric displacement field in a crystal which in turn will give rise to a voltage across the crystal. Near-future experimental setups that probe these two effects are applicable for axion masses between $10^{-11}\,\mathrm{eV}$ and $10^{-7}\,\mathrm{eV}$, a challenging range for most other detection concepts.

Speaker: Amalia Madden (Perimeter Institute)

piezoaxionic effect patras.pdf

14:30 → 15:10 Poster Lightning Talks: I

Convener: Gulden Othman (University of Hamburg)

14:30 Axion-like Dark Matter and the Cosmic Birefringence Signal

A detection of cosmic birefringence (rotation of linear polarization) has the potential to revolutionize our understanding of fundamental physics and cosmology. Several recent analyses of Planck 2018 and WMAP data have reported tentative evidence, at ~3$\sigma$ significance, of a cosmic microwave background (CMB) birefringence signal which appears isotropic, static and achromatic.

Dark matter in the form of axion-like particles (ALPs) can source cosmic parity violation. We calculate and present a distinct signal of isotropic CMB birefringence produced by ultra-light ALPs present at recombination as well as locally. Incorporating the allowed dark matter fractions over a large range of ultra-light ALP masses, strong constraints can be placed on the ALP-photon coupling: up to $ g_{a \gamma} < 10^{-16}$ GeV$^{-1}$ (from recombination) and up to $g_{a \gamma} < 10^{-13}$ GeV$^{-1}$ (local).

Upcoming CMB experiments (SO, CMB-S4, PICO & CMB-HD) have the promise to confirm or refute the evidence for birefringence and test its origin. Our forecasts show that calculated constraints on $ g_{a \gamma}$ can tighten further by 1-2 orders, extending them to higher ALP masses. If a cosmic birefringence signal is confirmed, one can specify the properties of ALP dark matter responsible for it.

CMB birefringence constraints on ALPs scale weakly with dark matter fraction. They are also unaffected by uncertainties which are common in other astrophysical ALP probes: the strength and spectrum of magnetic fields; an assumed over-density of ALP dark matter in structures or at centers of objects; and intrinsic polarization orientation.

Speaker: Dr Pranjal Trivedi (University of Hamburg)

PranjalTrivedi_AxionDM_Birefringence_17Patras_Mainz_08Aug22.pdf

14:33 Supermassive black holes as detectors for ultralight bosons

Ultralight bosons behave like coherent waves when the occupation number is large enough. If they are coupled to the Standard Model sector of the particle physics, such an oscillating background can induce a tiny signal. Near a fast rotating black hole, ultralight bosons within one order of the mass window can accumulate through superradiance with a large density expected. If linearly polarized radiation is emitted near the black hole, axion can contribute to birefringence effect that shifts the position angle periodically, making the polarimetric measurements of the Event Horizon Telescope on M87 a powerful way to look for ultra-light axions. On the other hand, the superradiance phase where black hole spin decreases exponentially can leave imprints on the shadow contour drift or azimuthal angle lapse of photon ring autorrelations, which makes future observations of SgrA optimal to look for such signals.

Speaker: Yifan Chen (ITP-CAS)

UBEHT_Patras_8.8.pdf

14:36 Towards sub-Hz ultralight dark matter searches with atom multi-gradiometry

Single-photon atom gradiometry is a powerful experimental technique that can be employed to search for the oscillation of atomic transition energies induced by ultralight scalar dark matter (ULDM). Previous studies have focused on the sensitivity reach of these experiments down to ULDM masses of $\sim 10^{-16}$~eV, which would induce a signal oscillating at $\sim 10^{-1}$~Hz, where gravity gradient noise (GGN) is expected to dominate over atom shot noise. In this talk, I'll provide a careful treatment of the dominant contribution to GGN that arises from surface Rayleigh waves and I will present a likelihood-based analysis that consistently folds GGN into the sensitivity estimates of vertical atom gradiometers, like AION and MAGIS, down to $\sim 10^{-2}$~Hz. Using this framework, we show that GGN can be significantly mitigated when operating three or more atom interferometers in the same baseline, which we define as an atom multi-gradiometer. In turn, this configuration would allow these large-scale quantum sensors to probe large parts of dark matter parameter space that are yet unconstrained by existing experiments.

Speaker: Mr Leonardo Badurina (King's College Lodond)

PatrasLightningTalk.pdf

14:39 Axion Production in Pulsar Magnetosphere Gaps

Pulsar magnetospheres admit non-stationary vacuum gaps that are characterized by non-vanishing $\bf{E} \cdot \bf{B}$. These gaps play an important role in plasma production and electromagnetic wave emission and, as I will discuss, are very efficient axion factories. The density of gap-produced axions in the vicinity of the pulsar can exceed the local dark matter density by many orders of magnitude. Once produced, a fraction of the axions will convert to photons in the strong pulsar magnetic field. The photons give rise to broadband radio signals that may be seen with dedicated observations of nearby pulsars with radio telescopes and interferometers. This proposal has the potential to probe axion-photons couplings that are orders of magnitude lower than current astrophysical bounds.

Speaker: Anirudh Prabhu (Stanford University)

Patras2022.pdf

14:42 Earth as a transducer for ultralight dark-matter detection

In this talk, I will propose the use of the Earth as a transducer for ultralight dark-matter detection. In particular I will point out a novel signal of both kinetically mixed dark-photon dark matter and axionlike dark matter: a monochromatic oscillating magnetic field generated at the surface of the Earth. Similar to the signal in a laboratory experiment in a shielded box (or cavity), this signal arises because the lower atmosphere is a low-conductivity air gap sandwiched between the highly conductive interior of the Earth below and ionosphere or interplanetary medium above. For dark-photon dark matter, the kinetic mixing with the Standard Model photon allows dark matter to convert into an observable magnetic field inside this cavity, while for axion dark matter, the background geomagnetic field of the Earth allows the axion to convert through its coupling to photons. The magnetic field signal of ultralight dark matter in a laboratory detector is usually suppressed by the size of the detector. Crucially, in our case the suppression is by the radius of the Earth, and not by the (much smaller) height of the atmosphere. The magnetic field signal exhibits a global vectorial pattern that is spatially coherent across the Earth, which enables sensitive searches for this signal using unshielded magnetometers dispersed over the surface of the Earth. I will summarize the results of such a search using a publicly available dataset from the SuperMAG collaboration. The dark-photon dark matter constraints from this search are complementary to existing astrophysical bounds, and the axion dark matter constraints are comparable to the bounds obtained by the CAST helioscope. Future searches for this signal may improve the sensitivity over a wide range of masses for both ultralight dark-matter candidates.

Speaker: Mr Saarik Kalia (Stanford University)

patras2022talk.pdf

14:45 Constraints on Dark Matter from the Eccentric Supermassive Black Hole Binary OJ 287

A dark matter overdensity around a black hole may significantly alter the dynamics of the black hole’s merger with another compact object. The strong gravitational potential of a black hole is theorised to lead to a significant increase in the concentration of dark matter in the central region with the creation of a “spike” in the dark matter density. We consider the case of OJ 287, which is a binary system containing a ∼ 18-billion solar mass primary black hole with a ∼ 150-million solar mass secondary black hole in an eccentric orbit, which triggers electromagnetic emissions twice in every ∼ 12 year period when it traverses the accretion disk of the primary. The accurate timing of those outbursts opens up the possibility of using this system to set constraints
on dark matter distributions containing OJ 287 (as well as testing general relativity in a
hitherto unexplored strong field regime) in the standard cold dark matter cosmogony. The times of the emissions are consistent with the predictions of general relativity calculated to the 4.5th post-Newtonian order. The orbit of the secondary black hole samples the gravitational field at distances between O(10) and O(50) Schwarzschild radii around the primary, and hence is sensitive to the possible presence of a dark matter spike around it. We find that the agreement of general-relativistic calculations with the measured timings of emissions from OJ 287 constrains the mass of such a spike to ≲ 3% of the primary mass.

Speaker: Ahmad Alachkar (King’s College London)

14:48 Wave dark matter structures

We analyze the dynamics of cosmological perturbations in models of dark matter based on ultralight coherent bosons. We discuss two different regimes in evolution, which distinguish between a particle-like behavior and a wave-like behavior. For different spins of this bosonic dark matter, the background evolution can contain non-vanishing vector and tensor modes. The evolution of scalar, vector and tensor perturbations can no longer be decoupled at the linear level in the wave regime. Therefore, small-scale density perturbations are necessarily associated with the presence of gravity waves. On the other hand, we also discuss the formation of clumps within the nonlinear regime. In this case, the self-interactions play a fundamental role. Depending on them, the clumps span a wide range of scales and masses, running from the size of atoms to that of galactic molecular clouds, and from milligrams to thousands of solar masses.

Speaker: J. A. R. Cembranos (Universidad Complutense de Madrid & IPARCOS)

PATRAS_Cembranos.pdf

14:51 ALP Dark Matter from Kinetic Fragmentation: Opening up the parameter window and Observational Consequences

Axion-like-particle (ALP) is a well-motivated candidate for dark matter, and it has been subject to extensive theoretical and experimental research in recent years. The most popular ALP production mechanism studied in the literature is the misalignment mechanism, where the ALP field has negligible kinetic energy initially, and it starts oscillating when its mass becomes comparable to the Hubble scale. Recently, a new mechanism called Kinetic Misalignment has been proposed where the ALP field receives large kinetic energy at early times due to the explicit breaking of the Peccei-Quinn symmetry. This causes a delay in the onset of oscillations so that the ALP dark matter parameter space can be expanded to lower values of the axion decay constant. At the same time, the ALP fluctuations grow exponentially via parametric resonance in this setup, and most of the energy in the homogeneous mode is converted to ALP particles. This process in known as fragmentation. In this talk, I will discuss the observational consequences of fragmentation for the axion miniclusters, and show that a sizable region of the ALP parameter space can be tested by future experiments that probe the small-scale structure.

Speaker: Cem Eröncel (DESY)

patras2022.pdf

14:54 UPLOAD: UPconversion Low-Noise Oscillator Axion Detection Experiment

UPLOAD is an axion detection experiment which is a variation upon the haloscope detector, using two resonant microwave modes within a cavity and removing the need of an external magnetic field. The effect of an external magnetic field is substituted by the overlap between the electric and magnetic field components of the two resonating modes themselves. As implied in the name, coupling between the photon modes and the axion field would be evidenced by upconversion of photons into the readout mode. As such, the targeted axion frequency is equal to the difference between the two resonating photon frequencies, dependent upon the chosen cavity geometry. The current experiment involves gigahertz electromagnetic modes, tunable via cavity height, separated by tens of megahertz, hence probing axions in the megahertz range. Two variations of the UPLOAD experiment have been constructed – one probing frequency noise induced on a readout mode, the frequency metrology method, and one probing power deposition in the readout mode, the power method. The frequency metrology method involves pumping both modes with synthesized signals and collecting Fourier spectra around the actively stabilized readout mode with a low noise frequency discriminator. The power method, in resemblance to a traditional haloscope, simply interrogates the thermal noise at the frequency of the readout mode for any axion-like interference peaks, while pumping power into the pump mode to boost SNR. This talk will cover experimental details and present axion exclusion limits derived from both experimental variations and discuss avenues for improvement and subsequent projected limits for future runs.

Speaker: Catriona Thomson (The University of Western Australia)

PATRASCThomsonLightningPoster.pptx

15:10 → 15:40 Coffee

15:40 → 16:10 Long talk: Session 2

Convener: Hendrik Bekker (HIM)

15:40 First constraints on axion-like particles from Galactic sub-PeV gamma rays

Experimental refinements and technical innovations in the field of extensive air shower telescopes have enabled measurements of Galactic cosmic-ray interactions in the sub-PeV (100 TeV to 1 PeV) range, providing new avenues for the search for new physics and dark matter. For the first time, we exploit sub-PeV (from 10 TeV to 1 PeV) observations of Galactic diffuse gamma rays by
Tibet AS$\gamma$ and HAWC to search for an axion-like-particle (ALP) induced gamma-ray signal
directly linked to the origin of the IceCube extragalactic high-energy neutrino flux. Indeed, the production of high-energy neutrinos in extragalactic sources implies the concomitant production of gamma rays at comparable energies. Within the magnetic field of the neutrino emitting sources, gamma rays may efficiently convert into ALPs, escape their host galaxy un-attenuated, propagate through intergalactic space, and reconvert into gamma rays in the magnetic field of the Milky Way. Such a scenario creates an all-sky diffuse high-energy gamma-ray signal in the sub-PeV range. Accounting for the guaranteed Galactic astrophysical gamma-ray contributions from cosmic-ray interactions with gas and radiation and from sub-threshold sources, we set competitive upper limits on the photon-ALP coupling constant $g_{a\gamma\gamma}$. We find $g_{a\gamma\gamma} < 2.3\times10^{-11}$ GeV$^{-1}$ for ALP masses $m_a \leq 2\times10^{-7}$ eV at a 95$\%$ confidence level, progressively closing the mass gap towards ADMX limits.

Speaker: Christopher Eckner (LAPTh, CNRS)

Eckner_TibetASg_HAWC_ALP_constraints_Patras2022.pdf

16:10 → 17:10 Poster Lightning Talks: II

Convener: Hendrik Bekker (HIM)

16:10 Millimeter-wave WISP search with lock-in Light-Shining-Through-a-Wall

The millimeter-wave photons are a crucial tool to address axion-like particles in the meV mass range, which is motivated in the post-inflationary scenario of axion. This mass range is the least constrained in the dark photon search as well. In dark matter halo WISPs search, it was reported that single photon sensors overwhelm the sensitivity of quantum-limited coherent detectors if the photon frequency is over 10 GHz. This is because the signal bandwidth is limited to Q~1e6 from the Maxwell Boltzmann distribution of dark matter halo. However, in the Light-Shining-Through-a-Wall (LSW) type experiments, one can phase-lock the coherent detectors to the generator so that the relative optical coherency becomes extremely high. Therefore, the signal bandwidth of LSW experiments can be several orders of magnitude higher than halo or solar WISPs search and the signal-to-noise ratio of the classical coherent method can surpass the single photon sensor. In this talk, we describe the implementation of the coherent detection method in the 30 GHz LSW method and show the results of proof-of-principle experiments. An EMC/EMI strategy to avoid cross-talks around 30 GHz is also presented. The expected search range is around the dark-photon mixing parameter of 1e-8 in the mass range of 1e-4 eV.

Speaker: Akira Miyazaki (Uppsala University)

miyazaki_patras2022_lightening_3min_3.pdf

16:13 Dark Matter Radio - 50 Liter

The axion is one of the most compelling dark matter (DM) candidates and a solution to the strong charge-parity problem. The DMRadio program consists of three experiments that together search for axions in the range 5 kHz - 200 MHz (20 peV - 0.8 $\mu$eV) with sensitivity to the DFSZ axion model: DMRadio-50L, DMRadio-m$^3$, and DMRadio-GUT. DMRadio-50L is a resonant lumped-element detector with a toroidal magnet searching for axions in the range 5 kHz - 5 MHz (20 peV - 20 neV) with a target sensitivity to axion-photon-photon coupling $5 \times 10^{-15}$ GeV$^{-1}$. DMRadio-50L also acts as an innovation platform and technology test bed for quantum sensors that will enable a next-generation search for GUT-scale axions in this mass region (DMRadio-GUT). This talk will provide an overview and status update of the DMRadio-50L experiment.

DMRadio-50L is supported by the Gordon and Betty Moore foundation and the Heising-Simons foundation. Quantum sensing work is supported under the DOE QuantISED program, and further support is provided by DOE and NSF grants to individual institutions.

Speaker: Kent Irwin (Stanford University and SLAC)

Irwin lightning presentation.pdf

16:16 Introducing the longitudinal ferromagnetic haloscope

A photon-magnon hybrid system naturally interacts with Dark Matter axions via the axion-electron coupling, and can therefore be used as an haloscope. We introduce a scheme where the axion field is detected through sidebands induced on a micorowave tone on resonance with cavity-magnon polaritons. The signal is proportional to the system quality factors and to the tone power, but, remarkably, not to the system volume, allowing for a pocket-size setup. The experimental configuration features a negligible tone noise and a high frequency readout, resulting in performances fundamentally limited by thermal or quantum fluctuations. We illustrate the detection scheme, present the results of a demonstrator experiment, and outline the possibilities for future developments.

Speaker: Nicolò Crescini (Institut Néel - CNRS)

LFH_patras22_nCrescini.pdf

16:19 Towards optimal extraction of dark matter signal from the Ly-alpha forest

The Ly-alpha forest traces the cosmic structure formation on smaller scales than complementary probes such as 21cm intensity mapping or CMB measurements. It is therefore well suited to study modern theories of fuzzy dark matter. However, the extraction of small scale structure information from the Ly-alpha forest poses some challenges as some of the observables become degenerate with the temperature of the IGM, the unknown peculiar velocities affect the spectral shapes of observed absorption features, the line saturation limits the range of observable densities and instrumental noise affects the predictive power of parameter estimations. In this presentation, I will discuss potential ways to overcome these challenges, achieve a full reconstruction of the underlying density field, and make optimal use of highest spectral resolution Ly-alpha forest data for constraining modern theories of dark matter.

Speaker: Hendrik Müller (MPIfR)

presentation.pdf

16:22 A first application of machine and deep learning for background rejection in the ALPS II TES detector

Axions and axion-like particles are hypothetical particles predicted in extensions of the standard model and are promising cold dark matter candidates. The Any Light Particle Search (ALPS II) experiment is a light-shining-through-the-wall experiment that aims to produce these particles from a strong light source and magnetic field and subsequently detect them through a reconversion into photons. With an expected rate $\sim1$ photon per day, a sensitive detection scheme needs to be employed and characterized. One foreseen detector is based on a transition edge sensor (TES). Here, we investigate machine and deep learning algorithms for the rejection of background events recorded with the TES. We also present a first application of convolutional neural networks to classify time series data measured with the TES.

Speaker: Manuel Meyer (University of Hamburg)

poster_lightning_talk_mmeyer_alps_patras2022.pdf

Poster_Patras2022_MLALPS_MMeyer.pdf

16:25 Comsol Simulation for Axions → FEM Simulation Study for Various Experiment Configurations.

Using commercial FEM software (COMSOL Multiphysics®), we solve the Axion- Maxwell equations in the geometrical context of experiments that search for axion and axion-like-particles (ALPs) dark matter. In this poster, we will present our approach to three different experimental setups.

Firstly, the BRASS-p is the pilot experiment that searches for axion/ALPs in the frequency range of 12-18 GHz (49.63 - 74.4 µeV). The combination of multiple FEM modules (AC/DC and RF modules) is used to explore the realistic magnetic field of the magnet panels and the axion-induced radiation. Accompanied with further studies concerning the efficiency and coherence effect of the overall setup.

Secondly, one can consider the possibility of detecting the skin current induced by the low mass axion dark matter (from kHz to a few of MHz, peV to neV) using a novel solenoid magnet. The theoretical foundation and simulation result will be discussed. Followed by the proposed approaches to pick up the signal using High Impedance Amplifier (HIA) and/or SQUIDS receiver.

Finally, we offer a closer look at the Weakly Interacting Slender Particle detection with LC circuit (WISPLC), an experiment that searches for axion/ALPs in the frequency range up to 2MHz using the pickup look inside the warm-bore solenoid magnet. We present our FEM solution for the implication of the presence of the superconducting coils on the pickup flux.

Speaker: Johannes Ulrichs

Patras_Poster_08.08.2022_julrichs.pdf

patras_teaser_2022_julrichs.pdf

16:28 Impedance Matching to the Axion

When seeking to understand symmetries of charge, parity, and time (the integral of phase), working in the easily visualized geometric representation of Clifford algebra rather than unintuitive matrix representations of Pauli and Dirac confers a remarkably clear and powerful perspective. Minimally complete vacuum wavefunction is the eight-component 3D Pauli algebra - 1 scalar, 3 vectors, 3 bivectors and 1 trivector - the same at all scales (Planck, Compton, deBroglie, galactic,...).

Combinations of the four fundamental constants that define the coupling constant $1/\alpha\simeq137$ permit assigning geometrically and topologically appropriate E and B flux quanta to the eight wavefunction components. Interactions are modeled by the dimension-changing geometric Clifford product, generating the S-matrix in flat 4D Minkowski spacetime of Dirac algebra. Time emerges from interactions.

Mass is quantized. All rest mass particles have quantized mechanical impedances, easily converted to electromagnetic. The resulting networks of S-matrix mode impedances govern amplitude and phase of energy flow within and between eigenstates, conferring a remarkably clear and powerful perspective on CPT symmetries and their breaking. In the poster we focus upon the axion.

Speaker: peter cameron (Michigan/MIT/Brookhaven (retired))

16:31 Relaxion dark matter from large fluctuations

Light scalar fields, such as axion-like particles (ALP), are promising dark matter candidates as they can be produced from the vacuum misalignment mechanism. In this work we investigate the mechanism in a less conventional regime where the ALP is subject to large fluctuations during its early dynamics. Our analysis is applied to the mechanism of cosmological relaxation of the electroweak scale, where the small value of the Higgs mass is selected dynamically by an ALP field i.e. the relaxion. We identify modified stopping conditions for such dynamics of the relaxion and find the new parameter space. In a wide region of the parameter space, the ALP can solve the hierarchy problem and, at the same time, account for the observed dark matter density in the universe. We describe various cosmological, astrophysical, as well as laboratory probes and constraints of such ALPs.

Speaker: Dr Aleksandr Chatrchyan (DESY T (Cosmology))

16:34 High-z Cosmic Web Statistics in Fuzzy Dark Matter Cosmologies

The vanilla Lambda cold dark matter (ΛCDM) model has been so successful that 2018 constraints from the Planck collaboration are based on the variation of the same 6 cosmological parameters as the analysis of the BOOMERanG 1998 data. Yet, the lack of evidence for any constituent particle and various small-scale challenges of the vanilla Lambda cold dark matter (ΛCDM) have generated considerable interest in alternative dark matter scenarios such as fuzzy dark matter (FDM). Cosmological hydrodynamical simulations of high-redshift galaxy and halo formation can help investigate tell-tale signs of FDM, which in turn inform observational searches. In this talk, I will start by discussing how FDM’s de Broglie scale-associated power spectrum cutoff modifies dark matter halo density and shape profiles. They reflect the broken hierarchy of structure formation which may have observable consequences. As a third Cosmic Web statistic, we will look at intrinsic alignment correlations of halos as predicted by the linear alignment model and will find statistically significant trends with the axion particle mass $m$. We cover masses in the range $m=10^{-22}-2\times 10^{-21}$ eV and focus on the high-redshift Cosmic Web in which dark matter signatures are more pristine than in today’s Universe.

Speaker: Tibor Dome (Institute of Astronomy, University of Cambridge)

2Slides_simple.pdf

16:37 ALP-EFTs for additionally gauged U(1) symmetries

We construct an effective theory (EFT) of an axion-like particle (ALP) for an additionally gauged $U(1)$ symmetry. The Z' is associated to a global current of the Standard Model (SM), such as baryon number ($B$) or baryon minus lepton number ($B-L$). In order to fulfill anomaly conditions as well as a trace condition, new fermions have to be introduced. Integrating out these fermions induces a kinetic mixing between the $\gamma$, Z and Z' bosons as well as the operators in the ALP-EFT. The matching conditions for the corresponding Wilson coefficients are determined by general calculations in which we allow all couplings to be flavor violating. We find new operators which are not covered by standard ALP-EFTs.

Speaker: Julien Laux (Johannes Gutenberg University Mainz)

Lightning_talk_Julien_Laux.pdf

16:40 Commissioning of Detection System for the Cosmic Axion Spin Precession Experiment (CASPEr)

CASPEr-Gradient searches for axion-like particles (ALP) which are a po-
tential dark matter candidate [1]. The gradient of the ALP field is predicted
to resemble a magnetic field in its coupling to nuclear spins [2]. Therefore, a
nuclear magnetic resonance (NMR) experiment is adopted to measure such a
gradient.

The NMR detection system has been commissioned for this research. We
performed a 10-hr measurement with thermally-polarized liquid methanol sam-
ple with a 25 ppm homogeneity at the 317 G leading field, which corresponds to
searching for an ALP field at 1.349 533 MHz with 34 Hz bandwidth. Noise and
ALP coupling constant exclusion are analyzed for the measurement.

References
[1] Derek F. Jackson Kimball et al. “Overview of the Cosmic Axion Spin Pre-
cession Experiment (CASPEr)”. In: Microwave Cavities and Detectors for
Axion Research. Ed. by Gianpaolo Carosi and Gray Rybka. Cham: Springer
International Publishing, 2020, pp. 105–121. isbn: 978-3-030-43761-9.
[2] Peter W. Graham and Surjeet Rajendran. “New observables for direct de-
tection of axion dark matter”. In: Phys. Rev. D 88 (3 Aug. 2013), p. 035023.
doi: 10.1103/PhysRevD.88.035023. url: https://link.aps.org/doi/
10.1103/PhysRevD.88.035023.

Speaker: Yuzhe Zhang (HIM)

16:43 Interface Between the Xenon-129 Polarizer and NMR Spectrometer in the CASPEr Dark Matter Experiment

An overview of hyperpolarized Xe transport and sample preparation as part of our experimental program to search for QCD axions and axion-like particles (ALPs) as possible candidates for DM using NMR techniques within the cosmic axion spin precession experiment (CASPEr) is presented [1]. The NMR signals from these particles will be very weak so all possibilities for signal enhancement need to be considered and for that, the chosen nuclei are 129-Xe that are hyperpolarized using the spin-exchange optical pumping (SEOP) technique inside a large optical cell. In this method, polarization is transferred to Xe via Fermi contact interactions with an optically pumped alkali metal. Especially for investigations of the nuclear spin resonance of liquid Xe as a fundamental physics experiment, a non-metallic variable temperature insert (VTI) is needed. This VTI should be suited for immersion in liquid helium. The sapphire sample holder is to hold on a level of 165 K ±1 K by a gaseous flow of temperature-stabilized nitrogen. Xe has a much higher spin density when it is liquid, thus it has to be kept in that narrow temperature range. The hyperpolarized Xe is then to be placed in a magnetic field that will be scanned up to 14.1 T looking for a possible resonance with the axion field, while the Xe nuclei undergo precession due to the gradient interaction. The first-generation experiments aim to explore many decades of ALP parameter space beyond the current astrophysical and laboratory bounds in the mass range of approximately 10-11 to 10-6 eV.

[1] Derek F. Jackson Kimball, et al. “Overview of the Cosmic Axion Spin Precession Experiment (CASPEr).” In Microwave Cavities and Detectors for Axion Research, edited by Gianpaolo Carosi and Gray Rybka, 105–21. Springer Proceedings in Physics. Cham: Springer International Publishing, 2020.

Speaker: Ophir Ruimi (Hebrew University of Jerusalem)

Ophir_slide_080822.pdf

Ophir_slide_080822.pptx

16:46 Production of hyperpolarized xenon-129 for the Cosmic Axion Spin Precession Experiment (CASPEr)

CASPEr-Gradient is an nuclear magnetic resonance (NMR) experiment seeking to detect axion-like-particles that could make up the dark matter present in the universe [1]. The detection is based on the coupling of the pseudoscalar dark matter field to nuclear spins. The strength of an NMR signal is proportional to the polarization of the sample. We can define the polarization as the relative difference in population between states of the system.
$\; \; \; \; \;$ In this talk, we present the spin-exchange optical pumping procedure [2] that is applied to hyperpolarize xenon. With this technique the polarization is increased significant compared to a thermally polarized sample determined by the Boltzmann distribution. The optimization of the polarization as well as improvements to the setup will be discussed.
$\newline$
$\normalsize{References}$
$\\$
[1] Jackson Kimball, Derek F., S. Afach, D. Aybas, J. W. Blanchard, D. Budker, G. Centers, M. Engler, et al. “Overview of the Cosmic Axion Spin Precession Experiment (CASPEr).” In Microwave Cavities and Detectors for Axion Research, edited by Gianpaolo Carosi and Gray Rybka, 105–21. Springer Proceedings in Physics. Cham: Springer International Publishing, 2020.https://doi.org/10.1007/978-3-030-43761-9_13
$\newline$
[2] W. Happer and W. A. Van Wijngaarden. “An optical pumping primer”. In: Hyperfine Interactions 38.1-4 (1987), pp. 435–470. ISSN : 03043843. DOI : 10.1007/BF02394855 .

Speaker: Mr Arian Dogan

16:49 Searching for Scalar Dark Matter and High Frequency Gravitational Waves with Mechanical Resonators

High quality factor bulk acoustic wave resonators provide a highly sensitive probe for fundamental physics research, as well as industry timing applications. When applied using the techniques and cryogenic technologies developed in the field of precision frequency metrology, these resonators can be used to place constraints on many emerging physical theories and even potentially detect new physics.

We present the summary of recent experimental work in which such piezo-electric bulk acoustic wave resonators have been used to constrain the parameters space of scalar dark matter using a novel analysis technique. We further show how the same resonator can be used to also search for high frequency gravitational wave (HFGW) signals by presenting our active and experimentally operational HFGW detection experiment: the Multimode Acoustic Gravitational-wave Experiment (MAGE), which has collected 153 days of real data in which rare events where detected. We outline the path for further work in how such resonator technology can be further used to push the boundaries of fundamental physics, exploring even more of Scalar DM parameter space and probing deeper into further new physics with experiment.

Speaker: William Campbell (The University of Western Australia)

WillCampbellPoster.pdf

16:52 Constraining heavy axion-like particles by energy deposition in Globular Cluster stars

Heavy axion-like particles (ALPs), with masses up to a few 100 keV and coupled with photons can be efficiently produced in stellar plasmas, contributing to a significant energy-loss. This argument has been applied to helium burning stars in Globular Clusters (GCs) to obtain stringent bounds on the ALP-photon coupling g_aγ. However, for sufficiently large values of the ALP mass and coupling to photons, one should expect a significant fraction of ALPs to decay inside the star. These ALPs do not contribute to the energy loss but rather lead to an efficient energy transfer inside the star. We present a new ballistic recipe that covers both the energy-loss and energy-transfer regimes and we perform the first dedicated simulation of GC stars including the ALP energy transfer. This argument allows us to constrain ALPs with m_a≲0.4 MeV and g_aγ≃10^−5 GeV^-1, probing a section of the ALP parameter space informally known as "cosmological triangle". This region is particularly interesting since it has been excluded only using standard cosmological arguments that can be evaded in nonstandard scenarios.

Speaker: Pierluca Carenza (Stockholm University, Oskar Klein Centre)

16:55 Shimming and SQUID detection for CASPEr-Gradient

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\Large
\begin{center}
Shimming and SQUID detection for CASPEr-Gradient\

\hspace{10pt}

\large
Julian Walter\

\hspace{3pt}

\small
juwalter@students.uni-mainz.de\
MAM section, HIM\
Johannes Gutenberg Universität Mainz

\end{center}

\hspace{7pt}

\normalsize

\noindent The Cosmic Axion Spin Precession Experiment (CASPEr) aims to detect axion-like particles (ALPs) using nuclear magnetic resonance (NMR)\cite{PhysRevD.88.035023}. ALPs are candidates for a light dark matter content of our universe. The CASPEr-Gradient Low-Field setup will probe the effect of local ALP background field gradients on the nuclear spins of hyperpolarized $^{129}Xe$ atoms, which would drive a precession of the sample spin axes around a leading magnetic field\cite{arXiv:1711.08999v3}.
\medskip\
The NMR signal is picked up by highly sensitive Superconducting Quantum Interference Devices (SQUIDs), test measurements of pulsed NMR have been made with thermally polarized liquid methanol samples.
\medskip\
Maximum homogeneity of the leading field in the sample region is required in order to improve the signal-to-noise ratio and reach the necessary precision to resolve ALP signals. To this end, eight independent ``shim" magnets are deployed around the main magnet to counteract field inhomogeneities. With automated optimization of the shim fields for each measurement run, we achieve a reduction of NMR signal line width from approximately $1000$ $ppm$ to $10$ $ppm$ within $50$ iterations, which is more efficient than a brute-force approach.

\printbibliography

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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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@article{arXiv:1711.08999v3,
title = {Overview of the Cosmic Axion Spin Precession Experiment (CASPEr)},
author = {D. F. Jackson Kimball et al.},
journal = {Instrumentation and Detectors (physics.ins-det)},
year = {2017},
month = {11},
doi = {10.48550/arXiv.1711.08999},
url = {https://arxiv.org/abs/1711.08999}
}

@article{PhysRevD.88.035023,
title = {New observables for direct detection of axion dark matter},
author = {Graham, Peter W. and Rajendran, Surjeet},
journal = {Phys. Rev. D},
volume = {88},
issue = {3},
pages = {035023},
numpages = {13},
year = {2013},
month = {Aug},
publisher = {American Physical Society},
doi = {10.1103/PhysRevD.88.035023},
url = {https://link.aps.org/doi/10.1103/PhysRevD.88.035023}
}

@InProceedings{10.1007/978-3-030-43761-9_13,
author="Jackson Kimball, Derek F.
and Afach, S.
and Aybas, D.
and Blanchard, J. W.
and Budker, D.
and Centers, G.
and Engler, M.
and Figueroa, N. L.
and Garcon, A.
and Graham, P. W.
and Luo, H.
and Rajendran, S.
and Sendra, M. G.
and Sushkov, A. O.
and Wang, T.
and Wickenbrock, A.
and Wilzewski, A.
and Wu, T.",
editor="Carosi, Gianpaolo
and Rybka, Gray",
title="Overview of the Cosmic Axion Spin Precession Experiment (CASPEr)",
booktitle="Microwave Cavities and Detectors for Axion Research",
year="2020",
publisher="Springer International Publishing",
address="Cham",
pages="105--121",
abstract="An overview of our experimental program to search for axion and axion-like-particle (ALP) dark matter using nuclear magnetic resonance (NMR) techniques is presented. An oscillating axion field can exert a time-varying torque on nuclear spins either directly or via generation of an oscillating nuclear electric dipole moment (EDM). Magnetic resonance techniques can be used to detect such an effect. The first-generation experiments explore many decades of ALP parameter space beyond the current astrophysical and laboratory bounds. It is anticipated that future versions of the experiments will be sensitive to the axions associated with quantum chromodynamics (QCD) having masses ≲10−9eV∕c2{\$}{\$}{{}{\backslash}lesssim {}}10^{{}-9{}}{\backslash},{\backslash}mathrm {{}eV{}}/c^2{\$}{\$}.",
isbn="978-3-030-43761-9"
}

Speaker: Julian Pascal Maximilian Walter (JGU)

Poster Lightning #28 Julian Walter.pdf

Poster Lightning #28 Julian Walter.pptx

16:58 Connection of GeV Dark Matter and Neutrino Floor with $(g-2)_{\mu}$ Anomaly in $U(1)_{L_{\mu}-L_{\tau}}$

We investigate the impact of recent anomalous $(g-2)_{\mu}$ measurement with $\sim 4 \sigma$ deviation from the SM, probing its effect on a light GeV scale fermionic dark matter (DM). The $(g-2)_{\mu}$ anomaly can be readily explained in the a beyond the SM (BSM) $U(1)_{L_{\mu}-L_{\tau}}$ scenario, where only a portion of hitherto allowed parameter space can explain the anomaly. This constraint impacts the enhancement of the neutrino floor, the neutrino background in the DM direct detection experiments. The GeV scale DM is severely constrained by the $(g-2)_{\mu}$ result as it restricts the $Z^{\prime}$ mass in the range of $20-200$ MeV. That restriction results in absence of s-channel resonant annihilation of the GeV scale DM, therefore resulting in over abundance of the DM relic. Even if a t-channel annihilation aided by large couplings can bring the relic density in the observed range, direct detection cross section shoots up. Consequently, super-GeV (with mass $1-10$ GeV) DM gets almost ruled out where as sub-GeV (with mass $0.1-1$~GeV) DM gets severely constrained.

Speaker: KULDEEP DEKA (University of Delhi)

KuldeepDeka-Patras-poster.pdf

Kuldeepdeka-Patras-teaser.pdf

17:10 → 19:00 Poster Session: I

19:00 → 22:00 Social Events: Welcome BBQ at Kulturcafe (QKaff) with Music

Tuesday 9 August

09:00 → 09:40 Invited talk: II

Convener: Manuel Meyer (University of Hamburg)

09:00 Experimental Searches for Invisible Axions

Motivated by theories beyond the standard model and/or astrophysical anomalies, axions and axion-like particles (or more generically weakly interacting slim particles) have received growing attention as candidates for addressing some fundamental questions in physics. There has been a tremendous effort to find hints of these hypothetical particles, with recent experimental searches starting to reach theoretically interesting levels of sensitivity. Continuous endeavors have also been made not only to enhance sensitivity by involving state-of-the-art technologies, but also to expand the search range by devising various methods according to the target mass. These orthogonal approaches will enable us to explore most of the parameter space within the next few decades in anticipation of answers to those fundamental questions. This talk reviews the current status of the search programs and discusses the future prospects.

Speaker: SungWoo Youn (IBS-CAPP)

Patras2022_YOUN_PDF.pdf

09:40 → 10:40 Contributed talks: III

Convener: Manuel Meyer (University of Hamburg)

09:40 DarkSide Status

DarkSide Status

Speaker: Małgorzata Harańczyk

Ds20kPATRAS2022_HaranczykV5.pdf

10:00 Axion dark matter search results around 9.5 μeV at CAPP with a high-temperature superconducting cavity

Superconducting radio frequency technology has played a significant role in the progress of precision measurements in particle physics experiments for decades. However, the presence of an external magnetic field could limit scientific productivity in many areas where a strong magnetic field is absolutely necessary. One specific example is a dark matter axion haloscope utilizing a microwave cavity (> 1 GHz) immersed in a high DC magnetic field (> 7 T). Having a high quality (Q) factor superconducting cavity would profoundly impact the way axion dark matter experiments are performed. Recently, the Center for Axion and Precision Physics Research (CAPP) successfully fabricated a half-million Q factor HTS cavities made of biaxially-textured GdBCO tapes. High-temperature superconducting (HTS) rare-earth barium copper oxide (ReBCO) is an excellent choice of material for realizing the high Q factor superconducting cavities for the axion search because of its characteristics such as ultra-low RF surface resistances (< 0.1 mOhm) at high magnetic fields and high depinning frequencies (> 10 GHz). The superconducting cavity was implemented in an axion detector with a quantum-noise-limited Josephson parametric amplifier (JPA) to collect axion dark matter physics data. We present the results of an axion dark matter search aiming at an axion mass range of around 9.5 μeV with KSVZ level sensitivity. This work is the first axion search result using an HTS cavity and also demonstrated the lowest total system noise (~190 mK) among published axion haloscope searches in phase-insensitive operations of JPA.

Speaker: Danho Ahn (KAIST, IBS/CAPP)

2022_August_PATRAS_Danho_Ahn_v7.pdf

10:20 COSINUS and NaI-based Dark Matter Experiments

COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) is a dark matter direct detection experiments investigating the nature of the annual modulation signal de- tected by the DAMA/LIBRA collaboration. A two-channel readout differentiates COSINUS from the other dark matter experiments using NaI-crystals: in addition to the scintillation light (measured with silicon light detectors), COSINUS can measure the heat released in the target after a particle interaction. The NaI-crystals are operated as cryogenic calorimeters and both the crystals and the silicon light detec- tors are equipped with Transition Edge Sensors (TES). The ratio between the amount of light and heat measured in the two channels is used to discriminate e−/γ-events from nuclear recoils on an event-by- event basis, thus it can provide further information on the nature of the DAMA/LIBRA signal. COSINUS has overcome the challenge of a low-melting-point and hygroscopic crystal by developing and successfully operating a new TES coupling named remoTES. It consists of a TES fabricated on a separated wafer and coupled to the NaI-absorber through a gold bonding wire and a gold foil glued on the NaI-surface. The required performance to cross-check the DAMA/LIBRA’s results is now within COSINUS’s reach. The construction of the facility hosting the new cryogenic observatory at the Gran Sasso National Laboratory (Italy) is progressing fast and planned to be complete by the end of 2023. In this talk, we provide a short overview of the state-of-the-art of the searches for the dark-matter-rate-annual-modulation and we describe the COSINUS detector design and optimisation, the current status of the facility and future plans.

Speaker: Vanessa Zema

PATRAS_2022_COSINUS.pdf

10:40 → 11:10 Coffee

11:10 → 12:30 Contributed talks: IV

Convener: Maria Simanovskaia (Stanford University)

11:10 First results for searches of exotic decays with NA62 in beam-dump mode

We report on the search visible decays of exotic mediators from data taken in “beam-dump” mode with the NA62 experiment.
The NA62 experiment can be run as a “beam-dump experiment” by removing the Kaon production target and moving the upstream collimators into a “closed” position.
In 2021, more than 10^17 protons on target have been collected in this way during a week-long data-taking campaign by the NA62 experiment. Using past experience, the upstream beam-line magnets were configured to sizably reduce background induced by ‘halo’ muons.
We report on the analysis results of this data, with a particular emphasis on Dark Photon Models.

Speaker: Alina Kleimenova

patras2022_na62_kleimenova.pdf

11:30 Status of the ALPS II Experiment

The Any Light Particle Search II (ALPS II) experiment will search for axion-like particles (ALPs) in an important parameter space that is relevant in understanding anomalous astrophysical phenomena, including stellar evolution. ALPS II takes advantage of the axion coupling to photons using a Light-Shining-through-a-Wall technique. Photons created using a strong laser may convert into ALPs in the presence of a strong magnetic field, traverse a light-tight barrier, reconvert into photons in another strong magnetic field, and be subsequently detected. By using two mode-matched optical resonators before and after the barrier, ALPS II aims to surpass the sensitivity of previous experiments by three orders of magnitude. In this talk, we will discuss the recent progress and current status of ALPS II as we move forward toward our first science run at DESY.

Speaker: Gulden Othman (University of Hamburg)

ALPS_GOthman.pdf

11:50 WISPFI: Searching for ALPs-Photon conversion on fiber interferometer

The Weak Interacting Slim Particles detection through a Fiber Interferometer (WISPFI) is conceived as a new experimental setup to search for light pseudo-scalars that couple to photons. The search for a light mass range is motivated by recent astrophysical observations [Majumdar, Calore, and Horns, 2018]. In that study, it was showed that gamma-ray observations of Galactic pulsars favor a mass range of $\left(3.6\pm 0.2\right)neV$ and an estimated di-photon coupling of $g_{a\gamma\gamma}=\left(2.3\pm 0.4\right)\times10^{-10}$ $GeV^{-1}$. The strongest constraint is from the OSQAR experiment [Ballou et al., 2015], which excludes $g_{a\gamma\gamma}$ $>$ $3.5$ $\times$ $10^{-8}$ $GeV^{-1}$ at 95 $\%$ confidence level.
Since these ranges have so far not yet probed in laboratory, this leads to the idea of performing this project. The WISPFI experiment has the potential to improve the sensitivity for laboratory-based searches considerably by using an innovative fiber-interferometric approach. WISPFI is based on a compact all-fiber Mach-Zehnder-type interferometer with the aim of using hollow-core photonic-crystal (HC-PC) fiber. This way, a compact design with a coiled-up fiber can be fit inside the warm-bore of a solenoid superconducting magnet of 14T field. The study addresses the search for weak-interacting slim particles (WISPs) by the use of experimental techniques used in the field of gravitational wave detection. This method allows to straightforwardly measure both the phase and amplitude changes in the presence of a non-vanishing $g_{a\gamma\gamma}$ and check for a possible signal.
The main idea is based on the proposal of Tam and Yang (2012).
The sensitivity of an interferometer to detect and measure the effect of the photon-mixing in a straight fiber relies on the conversion probability $p_{a\rightarrow \gamma}\propto g_{a\gamma\gamma}^{2}(BL)^{2}<<1$, where $BL$ is the product of the transversal magnetic field B and the length L over which the photon beam is passing through the magnetic field. That is although considering a proper media in which the effective mass of photons is comparable to the axion mass. However, providing the sufficiently large values of $BL$ to compensate the coupling factor can be challenging. In the light-shining-through-wall (LSW) experiments, the detection rate depends on the combined probability $p_{a\rightarrow \gamma}\propto g_{a\gamma\gamma}^{4}(BL)^{4}<<1$.\
The shot noise for a laser source of N photons is expected to scale with $\sqrt{N}$ following Poisson statistics.The sensitivity of the setup can be efficiently improved by increasing the power of the laser, $P_{laser}$ and implementing a squeezed light source with a squeezed factor S. The minimal coupling detectable is constrained by $g_{a\gamma\gamma}\propto S^{-\frac{1}{2}}P_{laser}^{-\frac{1}{2}}$. In conventional LSW-experiments the axion-photon coupling has a magnitude proportional to $g_{a\gamma\gamma}\propto P_{laser}^{-\frac{1}{4}}$. Regarding that, we estimate the sensitivity of the experiment for a resonant axion mass of 62meV using a hollow-core fiber to reach a detectable axion-photon coupling of $g_{a\gamma\gamma}<10^{-10}$ $GeV^{-1}$, with still marge of improvement with the implementation of squeezed light.
The development of a squeezed-light fiber interferometer is then necessary and is one of the objectives that are aimed to be fulfilled soon. This kind of interferometer is potentially interesting for its implementation in high-precision metrology applications.

Speakers: Josep Maria Batllori Berenguer (University of Hamburg), Mr Yikun Gu (University of Hamburg)

WISPFI_Patras_08092022.pdf

12:10 Xenon Status

Xenon Status

Speaker: Daniel Wenz

first_results_XENONnT_patras2022.pdf

12:30 → 14:00 Lunch

14:00 → 14:30 Long talk: II

Convener: Prof. Derek Jackson Kimball (California State University, East Bay)

14:00 The ORGAN Experiment: Results, Status, and Future Plans

We present the current status and future plans of the various experiments within The Oscillating Resonant Group AxioN (ORGAN) Collaboration, which develops microwave cavity axion haloscopes. ORGAN is a collaboration of various nodes of the ARC Centres of Excellence for Engineered Quantum Systems, and Dark Matter Particle Physics, and is primarily hosted at the University of Western Australia.

The ORGAN Experiment is a high mass haloscope (~60-200 micro-eV) broken down into various phases, having commenced in 2021, and running until 2026 [1]. Phase 1a recently concluded, excluding ALP Cogenesis models of dark matter in the mass range of 63 – 67 micro-eV [2]. Phase 1b is currently in commissioning, with Phase 2 in research and development. Active avenues of research and development for ORGAN include novel high frequency cavity design [3,4], superconducting materials, and single photon counting.

ORGAN-Q is a pathfinder experiment (~25 micro-eV), designed as a testbed for various techniques to be integrated into the main ORGAN Experiment in future phases, such as quantum-limited amplification, and other improvements.

ORGAN-Low Frequency is a lower-mass experiment (~1 micro-eV), designed to utilise an MRI magnet, and novel re-entrant cavities to push into the low frequency axion regime, and search for different models of dark matter.

We will summarize each experiment in terms of the relevant experimental details, current status, run plans, and projected reach.

1. Ben T. McAllister, Graeme Flower, Eugene N. Ivanov, Maxim Goryachev, Jeremy Bourhill, Michael E. Tobar, ‘The ORGAN experiment: An axion haloscope above 15 GHz’, Physics of the Dark Universe 18, 67-72
2. Aaron P. Quiskamp, Ben T. McAllister, Paul Altin, Eugene N. Ivanov, Maxim Goryachev, Michael E. Tobar, ‘Direct Search for Dark Matter Axions Excluding ALP Cogenesis in the 63-67 micro-eV Range, with The ORGAN Experiment’, Science Advances (accepted, in production), arXiv:2203.12152
3. Ben T. McAllister, Graeme Flower, Lucas E. Tobar, and Michael E. Tobar, ‘Tunable Supermode Dielectric Resonators for Axion Dark-Matter Haloscopes, Phys. Rev. Applied 9, 014028
4. Aaron P. Quiskamp, Ben T. McAllister, Gray Rybka, and Michael E. Tobar, ‘Dielectric-Boosted Sensitivity to Cylindrical Azimuthally Varying Transverse-Magnetic Resonant Modes in an Axion Haloscope’, Phys. Rev. Applied 14, 044051

Speaker: Ben McAllister

Patras22F.pdf

14:30 → 15:10 Poster Lightning Talks: III

Convener: Prof. Derek Jackson Kimball (California State University, East Bay)

14:30 Testing the mean field description of scalar field dark matter

The nature of dark matter, one of the major components of the cosmic standard model, remains one of the outstanding problems in physics. One interesting model is scalar field dark matter (SFDM), which fits naturally into observations in both particle physics and cosmology. Simulations and calculations using SFDM often use a classical field approximation (MFT) of the underlying quantum field theory. And while it is suspected that large occupation numbers make this description good in the early universe, it is possible that this approximation fails during nonlinear structure growth and begins to admit important quantum corrections. To investigate this possibility, we compare simulations using the MFT to those that take into account these corrections. By studying their behavior as we scale the total number of particles in the system we can estimate how long the MFT remains an accurate description of the system. We estimate this time scale for a typical halo may be of order ~1 Gyr, short compared to the age of the universe. In this talk we will explain how these simulations are performed, as well as their results, and their potential implications.

Speaker: Andrew Eberhardt (Stanford University)

PATRAS.pptx

14:33 Collision Rates of Axion Stars with astrophysical Objects

Bose stars are gravitationally bound Bose-Einstein-Condensates in which the kinetic quantum pressure is stabilized by the self-gravitation and self-interaction of the scalar field.
In recent years, several interactions between these Condensates and astrophysical objects have been proposed: Bose star merger events could lead to supercritical soliton states, which can either shed a large fraction of their mass through relativistic Axion emission [1] or steadily emit radio photons given suitable Axion-Photon coupling $g_{a\gamma\gamma}$ [2, 3]. Similarly, the interaction of Bose stars with the strong magnetic fields of neutron stars could lead to enhanced photon emission [4, 5].
This talk gives a short overview about the fundamental properties of Bose stars - their condensation time scales, accretion rates and the mass-radius relation for QCD Axion stars. Considering these properties, we develop a formalism to precisely calculate collision rates for a broad range of Axion stars with the most abundant astrophysical objects in the milky way: ordinary stars, white dwarves, neutron stars, stellar black holes, planets and other Axion stars.
We re-evaluate from our results the likelihood of events and the possibility of future detection for several Axion star interactions and for different values of the Axion mass and coupling. We conclude by proposing physically motivated mass distributions for QCD Axion stars and demonstrate how this affects the likelihood of interactions.

Speaker: Dennis Maseizik (II. Institut für theoretische Physik)

Maseizik - Lightning Talk - 4-3 ratio.pdf

Maseizik - Lightning Talk.pdf

14:36 Black hole superradiance of self-interacting scalar fields

Black hole superradiance is a powerful probe of light, weakly-coupled hidden sector particles. Many candidate particles, such as axions, generically have self-interactions that can influence the evolution of the superradiant instability. As pointed out in arXiv:1604.06422 in the context of a toy model, much of the existing literature on spin-0 superradiance does not take into account the most important self-interaction-induced processes. These processes lead to energy exchange between quasi-bound levels and particle emission to infinity; for large self-couplings, superradiant growth is saturated at a quasi-equilibrium configuration of reduced level occupation numbers. In this paper, we perform a detailed analysis of the rich dynamics of spin-0 superradiance with self-interactions, and the resulting observational signatures. We focus on quartic self-interactions, which dominate the evolution for most models of interest. We explore multiple distinct regimes of parameter space introduced by a non-zero self-interaction, including the simultaneous population of two or more bound levels; at large coupling, we confirm the basic picture of quasi-equilibrium saturation and provide evidence that the "bosenova" collapse does not occur in most of the astrophysical parameter space. Compared to gravitational superradiance, we find that gravitational wave "annihilation" signals and black hole spin-down are parametrically suppressed with increasing interactions, while new gravitational wave "transition" signals can take place for moderate interactions. The novel phenomenon of scalar wave emission is less suppressed at large couplings, and if the particle has Standard Model interactions, then coherent, monochromatic axion wave signals from black hole superradiance may be detectable in proposed axion dark matter experiments.

Speaker: Olivier Simon

lightning talk.pdf

14:39 Challenging the Stability of Light Millicharged Dark Matter

So far, there is no experimental evidence of dark matter interacting with electromagnetism. Naively, this rules out any sizeable electric charge assigned to dark matter particles, thereby suppressing interactions with photons. Consequently, it is often taken for granted that a light dark matter candidate carrying a tiny electric charge is cosmologically stable. In this talk, I will argue that this is not necessarily the case. Quite the contrary, the fact that very light bosonic dark matter is long-lived is far from trivial.

Speaker: Sebastian Schenk (IPPP Durham)

schenk_patras2022.pdf

14:42 The VMB@CERN experiment

Nonlinear electrodynamic effects in vacuum have been predicted since the early days of Quantum Electrodynamics (QED) with the formulation of the Euler effective Lagrangian in 1935. Vacuum magnetic birefringence is one of these effects. Although experimental efforts have been active for more than 40 years, a direct laboratory observation of vacuum magnetic birefringence is still lacking as the effect is extremely small ($\Delta n = 4\times10^{-24}$ @ B = 1T).
In order to detect such small birefringences, experiments employ high-sensitivity polarimeters and long optical paths in intense magnetic fields. Fabry-Perot optical cavities usually provide the required increase in optical path. Unfortunately, none of the previous experiments reached shot noise-limited sensitivity: the cavity mirrors generate a birefringence noise that is enhanced by the cavity in the same way as the vacuum birefringence signal.
The VMB@CERN collaboration proposed in 2019 an experimental setup to overcome the intrinsic mirror noise limit by employing a spare LHC superconducting magnet and a new polarization modulation scheme that uses two co-rotating half-wave plates inside the optical cavity. A proof of principle feasibility study for the experiment is currently underway at the INFN unit of Ferrara. I will present measurements of the systematic effects in our polarimeter and the methods we used to reduce them to establish the first locks of the optical cavity with the rotating half-wave plates.

Speaker: Giuseppe Messineo (INFN Ferrara)

Messineo-Patras22.pdf

Messineo-Patras22-teaser.pdf

14:45 Searching for ultralight dark matter with spectroscopy of radio-frequency atomic transitions

We report on ongoing experimental searches for fundamental constant (FC) oscillations which are motivated within models of ultralight scalar dark matter (DM). In one search, the frequency of a bulk acoustic-wave quartz oscillator is compared to the frequency of the ${}^{87}$Rb ground-state hyperfine transition [1], to look for oscillations of the electron mass $m_e$, fine structure constant $\alpha$, and nucleon mass $m_N$, in the frequency range 1.6 mHz-200 Hz (underlying DM particle mass range $6.9\times10^{-18}< m_{\phi} < 8.27\times10^{-13} eVc^{-2}$). In another search carried out in the same frequency range, a radio-frequency electronic transition in ${}^{164}$Dy is probed to look for oscillations in the fine-structure constant [2], exploiting the extreme sensitivity of the transition frequency to changes of this constant. Preliminary results are presented, based on data from a 25-day long quartz-Rb run, and a 12-hr long Dy run. In the absence of detection of FC oscillations, we constrain the DM coupling to $\alpha$, $m_e$ and $m_N$. The constraints on $\alpha$ from the Dy experiment improve on previous results by as many as three orders of magnitude, while the results on the couplings to $m_e$ and $m_N$ from the Rb-quartz experiment improve on previous constraints by an order of magnitude in part of the explored parameter space.

[1] W. M. Campbell et al. PRL 126, 071301 (2021).
[2] K. V. Tilburg et al. PRL 115, 011802 (2015).

Speaker: Xue Zhang (Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany and Helmholtz-Institut, GSI Helmholtzzentrum für Schwerionenforschung, 55128 Mainz, Germany)

lightning talk_Xue.pdf

14:48 Axion Vacua

In this talk, we discuss recent computational advances in generating axion systems directly from Type IIb string geometries, including full axion spectra and vacua statistics, and show different methods in which these can put constraints on the landscape of possible compactifications, e.g. black hole superradiance.

Speaker: Viraf Mehta

patras_lightning_VMM.pdf

poster_patras_VMM.pdf

14:51 Improving the solar axion-electron limit with a GridPix detector at CAST

The CERN Axion Solar Telescope (CAST) was a solar axion helioscope,
which produced the most stringent limits on multiple different
axion like particle candidate couplings by utilizing the inverse Primakoff
effect to convert particles into X-rays in a transverse magnetic field.

A gaseous detector based on 7 GridPixes, a combination of a $256 \times 256$ pixel Timepix ASIC and an integrated MicroMegas stage on
top, together with veto scintillators and an FADC, was installed at
CAST in 2017/18. It recorded a total of about $3500\,h$ of
background and $180\,h$ of solar tracking data.

This talk will present the data analysis and limit calculation method
developed for this detector. The method aims to be model agnostic,
allowing for limit calculations on different coupling constants,
provided the solar flux for the particle can be modeled. The focus
will be on a new, improved limit on the the axion-electron coupling
$g_{ae}$ over the previous 2013 limit.

Speaker: Sebastian Schmidt (Universität Bonn)

patras_lightning_talk.pdf

14:54 Novel Method for the Detection of Axions by Daily Modulations

Standard axion search methods rely on resonant cavities with a strong magnetic field.
These cavities must be tuneable in discrete steps to search for axions with small linewidths.
In this talk we will discuss a different method for searching for axions based on broadband
search ideas. Specifically we will focus on the Axion Quark Nugget (AQN) model. The
AQN model is based on earlier quark nugget model with an added axion domain wall which
stabilizes the quark nugget. Axions produced in this model travel with a velocity of v 0.6c.
This means that line width of axions from the AQN model will be large ( 1 GHz) and this
will require a new detection strategy. We will discuss new methods for detecting broadband
axions including a search for daily modulations which, up until now, have been up until
now ignored in the literature. The idea is to collect the signal over entire season during
a specific hour and fitting the resulting power excess as a function of time (measured in
hours) during 24 hours period. We will discuss how a genuine signal can be discriminated
from a spurious signal and background noise by considering B=0 data and by studying the
phase drift of the daily modulations. Finally we will comment on how these broadband
searches may be applied to current axion cavity experiments.

Speaker: Connor Adair (Univeristy of British Columbia)

patras-axion-pres.pdf

14:57 New prospects for the axion dark-matter search brought by the advanced GNOME sensor

In recent years, optically-pumped magnetometers (OPMs) have been successfully used for setting new constraints on possible parameters of transient exotic spin couplings of axion dark matter. This was achieved with the help of the Global Network of Optical Magnetometers for Exotic physics searches (GNOME), being a world-wide network of synchronized magnetometers located in Europe, Asia, Australia, and USA. However, the GNOME network can be improved by implementing a new type of sensors that is less prone to magnetic-field noise. This can be achieved by implementation a noble-gas-alkali-metal comagnetometers. These sensors allow a sensitivity gain to exotic spin couplings of protons and neutrons of three to five orders of magnitude. Moreover, in certain conditions comagnetometers allow to distinguish between magnetic and nonmagnetic spin perturbations. This is a significant advantage of the system compared to the conventionally used OPMs, as it allows to discriminate nonmagnetic couplings events.

We will present the results of the tests of the system with nonmagnetic spin couplings generated with rotation and AC Stark effect, which was used to simulate nonmagnetic spin perturbations targeted by GNOME. We will also discuss other particular dark-matter signatures, that can be observed with the sensor.

Speaker: Mikhail Padniuk (Marian Smoluchowski Institute of Physics, Jagiellonian University in Krakow)

Poster lightning talk.pptx

15:00 Novel calibation of XENON1T at lowest energies with 37Ar

Novel calibation of XENON1T at lowest energies with 37Ar

Speaker: Christopher Hils

AdvertisementSlides_Patras2022_37Ar_CHils.pdf

15:03 Axion searches based on $Q_0 \approx 10^{10}$ multimode superconducting cavities

The SQMS Physics and Sensing thrust is working toward the implementation of multiple axion search schemes to improve upon the current state-of-the-art sensitivity. The search schemes here under consideration all utilize either single or multiple ultra-high Q SRF cavities. Rather than applying an external magnetic field, these searches take advantage of the cavity resonant modes to enhance the production and/or detection of axions in the cavity volume. We are actively working on the design of two searches. We are also carrying out multi-mode and single mode non-linearity measurements as part of an experimental feasibility study to gain insight on the behavior of the ultra-high Q resonators and the RF system in the regime relevant for axion searches.

Speaker: Dr Sam Posen

BGiaccone_Patras_LightningTalk[46] - Read-Only.pdf

15:10 → 15:40 Coffee

15:40 → 16:10 Long talk: IV

Convener: Kristof Schmieden (JGU Mainz)

15:40 Gravitational Focusing of Dark Matter Streams in Solar Neighborhood and Implications for Detection

Cosmological models of dark matter in the galaxy reveal more intricate features than a smooth standard Halo model. One of the features is the existence of numerous fine-grained streams at the location of the solar system, where these fine-grained streams have small velocity dispersion owing to the cold non-interacting nature of dark matter. The gravitational focusing of dark matter by the solar system bodies including the Sun and the Moon has been explored previously. These studies have shown that a small modulation in dark matter density would result at Earth’s location if velocity profile of dark matter is Maxwellian which is the assumption in the standard Halo model. The semi-analytic models indicate however large density enhancement are possible for streaming dark matter. We developed simulation tools to propagate dark matter particles such as WIMPs or axions from these streams in our neighborhood accounting for cumulative gravitational effect of Sun and Earth, velocity dispersion effects, and multiple streams overlap. We comment on density enhancement and implications for detection. While our tools have been focused on fine grained streams they could be used for any incoming phase space propagation of dark matter particles in solar vicinity.

Speaker: Abaz Kryemadhi (Messiah University)

DM_Streams_Talk_PatrasWorkshop2022.pptx

16:10 → 17:10 Poster Lightning Talks: IV

Convener: Kristof Schmieden (JGU Mainz)

16:10 The importance of quantum loops for astrophysical ALPs

We investigate the effect of quantum loops on the theory of axionlike particles (ALPs) coupled to electrons. Contrary to some statements in the recent literature, the effective ALP-photon coupling induced by an electron loop can be sizeable in the plasma of a supernova. We define a general effective coupling that depends on the kinematics of the specific process in which an ALP scatters, decays, or is produced. Using this effective coupling, it can be shown that production of ALPs by loop processes is in fact slightly more efficient than the respective tree-level processes in a numerical model of SN1987A. We update the bound on $ g_{ae} $ imposed by the observed duration of the neutrino burst of SN1987A. Moreover, we derive a new bound, which does not exist at tree-level for ALPs only coupled to electrons, from the non-observation of gamma-rays from ALP decays directly after the initial neutrino burst was observed in 1987. These are the leading constraints on $ g_{ae} $ in the ALP-mass range of roughly $ 30 \text{ keV}$ to $300 \text{ MeV} $.
Using the effective coupling, we furthermore point out that ALP dark matter coupled to electrons is not stable in the $ \text{keV} $ mass range due to loop-induced decays into photons. Large parts of the parameter space that direct detection experiments are sensitive to are therefore either (i) incompatible with the assumption of ALPs being dark matter as their lifetime is shorter than the age of the universe, or are (ii) already excluded by indirect detection searches for x-rays and gamma-rays as products of ALP decays.

Speaker: Eike Müller (Stockholm University)

EMueller_Patras2022.pdf

16:13 A self-consistent wave description of axion minicluster and their survival in the galaxy

We present a solution of the Schrodinger–Poisson system based on the WKB
ansatz for the wave function. In this way we obtain a description of a gravitationally bound
clump of axion dark matter by a superposition of energy eigenstates with random phases. It
can be applied to any self-consistent pair of radial density distribution and phase space den-
sity f (E) related by Eddington’s formula. We adopt this as a model for axion miniclusters in
our galaxy and use it to study the mass loss due to a star encounter by using standard pertur-
bation theory methods known from quantum mechanics. Finally, we perform a Monte Carlo
study to estimate the surviving fraction of axion miniclusters in the dark matter halo of our
galaxy. We find that the reaction to perturbations and the survival probability depend cru-
cially on the density profile. Weakly bound clusters are heated up and eventually destroyed,
whereas more strongly bound systems get even more compact as a result of perturbations
and are driven towards an axion star configuration.

Speaker: virgile Dandoy (Karlsruhe Institute of Technology)

V.Dandoy Patras (1).pdf

16:16 Updated bounds on ALP Dark Matter with the optical MUSE-Faint survey

We provide bounds on the effective axion-like particle (ALP) to two-photon coupling obtained from the MUSE spectroscopic observations of six dwarf spheroidal galaxies between 470 and 935 nm. We search for the signal from radiative decays of ALPs under the assumption that they constitute the dark matter component of the haloes. These bounds are an update to those of arXiv:2009.01310 [astro-ph.CO].

Speaker: Elisa Todarello (University of Turin)

talk.pdf

16:19 Simulations of axionlike particles in the post-inflationary scenario

In the scenario in which the axion is born after inflation, the field develops significant inhomogeneity and evolves in a highly nonlinear fashion. Understanding the eventual abundance and distribution of axionic dark matter in this scenario therefore requires dedicated numerical simulations. Here, we go beyond the QCD axion, and perform a suite of simulations for a range of possible temperature dependencies in the axion mass growth, including the temperature independent axion-like particle case. We study the complex dynamics of the axion field's evolution, including the scaling of the axion cosmic string network, the decay of domain walls, and the lifetime of axitons; eventually leaving us with the seeds of miniclusters. Given the expanding experimental campaign to search for axions and axion-like particles, these simulations have potentially wide implications for present-day direct and indirect searches.

Speaker: Giovanni Pierobon (University of New South Wales)

Patras_summary.pdf

16:22 Obtaining Small Kinetic Mixing in String Theory

Kinetic mixing between 𝑈(1) gauge groups is a well-known possible interaction between our visible Standard Model sector and a hidden sector supposed to contain dark matter. Naturally, the mixing coupling must be very small for the hidden sector to remain “almost” completely hidden. We aim to follow up on the established literature and investigate how very small kinetic mixing can arise in string theory compactifications. In particular, we focus on the large volume scenario in type IIB. Small kinetic mixing can be attained by tuning the hidden gauge coupling to small values, embedding the 𝑈(1)s in non-abelain gauge groups or by sequestering the visible and hidden sector. We elaborate why tiny gauge couplings are unsatisfactory since they reduce the cutoff of the 4-dim. effective theory. Considering the large volume scenario, we show that the hidden gauge coupling is bounded from below, thus excluding kinetic mixing of $𝜒 ≲ 10^{−12}$. Driven by phenomenology, we advocate a “minimal setup” for stringy kinetic mixing incorporating charged states and evading the issues related to tiny gauge couplings. In this minimal setup, small kinetic mixing is achieved: 1) by embedding the 𝑈(1)s in non-abelian gauge groups, 2) by sequestering the visible and hidden sector hosted on D-brane stacks. Surprisingly, it turns out that the naive approach by simply separating the visible and hidden D-branes over long distances in the Calabi-Yau manifold is not sufficient to achieve exponentially suppressed kinetic mixing. We also discuss how a charge conjugation symmetry, which forbids kinetic mixing, can be realized in type IIB.

Speaker: Ruben Kuespert (MPIK / ITP Heidelberg)

Kuespert_PATRAS_Lightning_Talk.pdf

16:25 A TES for ALPS II

The Any Light Particle Search ALPS II is a light-shining-through-a-wall (LSW) experiment
to investigate the existence of axions and axion-like-particles (ALPs) in the sub-meV mass range. The existence of these particles is motivated by multiple quarters, from QCD to stellar physics. ALPS II aims to convert 1064 nm photons into axions or ALPs aided by the presence of a magnetic field, in an optical cavity. After passing through a light-tight barrier, these particles reconvert to photons in another optical cavity in a magnetic field, before subsequent detection. The expected signal amounts to about one 1064 nm photon per day, necessitating a detector capable of observing this low regenerated photon rate $\mathcal{O}(10^{-5})$ cps with a correspondingly low background rate at this low energy, with high detection efficiency. These demands can be met by a transition edge sensor (TES), a cryogenic microcalorimeter, employing the drastic variation in its resistance at its superconducting transition temperature. The experimental details of this detection setup, its operation, and characterisation are described. With an energy resolution $\sim$10% and a viably low (intrinsic) background rate demonstrated, tests to optimise its efficiency, to diagnose, simulate and suppress backgrounds, and to probe its use for other physics goals are ongoing. These results and investigations will be discussed, as well as the planned implementation of the TES in ALPS II in 2023.

Speaker: Rikhav Shah (JGU Mainz)

PosterLightning Talk_Patras2022_RShah_TES.pdf

RShah_TESforALPSII_Patras2022.pdf

16:28 Luminous black holes

A complimentary scenario to superradiance is presented based on the possible existence of insta-
bilities in non-rotating black holes. A plausible parameter space for the formation of axion-type
scalar field clouds around black holes in cosmological times is determined, which allows establishing
bounds on the amount of dark matter as primordial black holes through axion-photon coupling.
Additional phenomenological results are commented on.

Speaker: Yadir Garnica (Division de Ciencias e Ingenier ́ıas, Universidad de Guanajuato)

Sildes-LBH.pdf

16:31 Implications of the cosmic birefringence measurement for the axion dark matter search

We show that a recent constraint on the cosmic birefringence effect due to dark energy can be related to the constraints on the coupling of axion dark matter to photon, by relying on a simple model of two-axion alignment mechanism with periodic potentials. Owing to the alignment of the potentials, one linear combination of two fields provides a nearly flat direction and acts as dark energy, whereas the other combination provides a steep direction and acts as dark matter. This scenario solves the known conceptual issues of one-field model for dark energy and predicts the connection between seemingly disparate constraints on the dark sectors of our universe.

Speaker: Ippei Obata (Max-Planck-Institute for Astrophysics)

Patras2022_Obata.pdf

16:34 Detection of very small structures of dark matter with direct detection experiments

The study of the density profile of dark matter (DM) on small scales provides valuable information about the mass distribution within the Galaxy and can predict new compact objects.
We take the sensitivity projections of future direct detection experiments to predict the observation times needed to detect small DM overdensities, assuming a DM cross section close to the current limit of $\sigma_{SI} = 2 x 10^{-47}$ cm$^2$. We present DM power spectrum locally in numerical simulations using a simplistic description. We compare the density imprints of homogeneous DM with those of large overdensities. We then perform statistical tests to show that with a range of (50, 200) numbers of events and observation times of the order of ~ 5 years we can observe structures of size $10^9 h Mpc^{-1}$ with an overdensity of order $\rho/\rho_0 \sim 10$.

Speaker: Valentina Montoya (ITP, Heidelberg University)

patras.pdf

16:37 Searching for dilaton fields in the Lyalpha forest

Dilatons (and moduli) couple to the masses and coupling constants of ordinary matter, and these quantities are fixed by the local value of the dilaton field. If, in addition, the dilaton with mass mφ contributes to the cosmic dark matter density, then such quantities oscillate in time at the dilaton Compton frequency. We show how these oscillations lead to broadening and shifting of the Voigt profile of the Lyα forest, in a manner that is correlated with the local dark matter density. We further show how tomographic methods allow the effect to be reconstructed by observing the Lyα forest spectrum of distant quasars. We then simulate a large number of quasar lines of sight using the lognormal density field, and forecast the ability of future astronomical surveys to measure this effect. We find that in the ultra low mass range 10−32 eV ≤ mφ ≤ 10−28 eV upcoming observations can improve over existing limits to the dilaton electron mass and fine structure constant couplings set by fifth force searches by up to five orders of magnitude. Our projected limits apply assuming that the ultralight dilaton makes up a few percent of the dark matter density, consistent with upper limits set by the cosmic microwave background anisotropies.

Speaker: Mr Louis Hamaide (King's College London)

3min PATRAS - LH presentation 08-22.pdf

Poster PATRAS - LH 08-22.pdf

16:40 Axion Gegenschein: Dark Counterimages of Bright Radio Sources

Axion-like particles (ALPs), promising particle candidates of dark matter, can decay into photons through their electromagnetic couplings. However, thanks to their very large lifetime, they are extraordinarily stable. While exposed to ambient radiation of similar frequency as their mass, the decay rate of ALPs into photons is dramatically enhanced resulting in a detectable flux of photons, a phenomenon often termed as the stimulated decay of ALPs.

When photons from radio-bright astrophysical objects such as distant AGNs and SNe remnants pass through the dark matter halo of the Milky Way, they can induce stimulated decay of QCD-scale ALPs each resulting in two photons traveling in directions opposite to one another. While observing in the direction opposite to the source from the observer along the line of sight, photons from stimulated ALP decay appear as radiation that has been backscattered precisely opposite to the incoming wave. We propose a novel detection framework to look for radio emissions from these counterimages of the astrophysical source, named Axion Gegenschein, analogous to the zodiacal light observed in the antisolar direction.

The detectable radio emission should have the spectrum of a narrow emission line, with a width determined by the axion velocity dispersion. Correspondingly, the counterimage should have the same morphology and dimension as the astrophysical source with a localization in a direction diametrically opposite to it, which constitute a unique signature of decaying ALPs that cannot be mimicked by other astrophysical phenomena. We show the sensitivity of this powerful technique in current and future-generation radio telescopes and discuss the advantages over other probes of radio emission from stimulated ALP decay.

Speaker: Oindrila Ghosh (II. Institute for Theoretical Physics, University of Hamburg)

O_Ghosh_Axion_Gegenschein.pdf

16:43 Axion signatures from supernova explosions through the nucleon electric-dipole portal

We consider axions coupled to nucleons and photons only through the nucleon electric-dipole moment (EDM) portal. This coupling is a model-independent feature of QCD axions, which solve the strong CP problem, and might arise as well in more general axion-like particle setups. We revise the supernova (SN) axion emission induced by the nucleon EDM coupling and refine accordingly the SN 1987A bound. Furthermore, we calculate the axion flux from a future Galactic SN and show that it might produce a peculiar and potentially detectable gamma-ray signal in a large underground neutrino detector such as the proposed Hyper-Kamiokande. The possibility to detect such a signal offers a way to search for an oscillating nucleon EDM complementary to CASPERe, without relying on the assumption that axions are a sizeable component of the dark matter. Furthermore, if axions from SN produce an observable signal, they could also lead to an amount of cosmological extra-radiation observable in future cosmic surveys.

Speaker: Giuseppe Lucente (Bari University & INFN Bari)

Lucente_PATRAS2022.pdf

16:46 Intensity interferometry for ultralight bosonic dark matter detection

Ultralight bosons with masses bellow 1 eV/c² are a promising candidate to be a predominant component of dark matter. These particles can be described by a classical wave-like field oscillating near the Compton frequency of the bosons. Assuming that they are virialized in the galactic gravitational potential, the random velocities produce slight deviations from the Compton frequency. These result in a near-zero-frequency (dc) stochastic fluctuation of the amplitude of the field on a time scale determined by the spread in kinetic energies.

Ultralight bosonic dark matter can couple to Standard Model (SM) particles through a variety of interactions. If a measurement scheme for the direct detection is sensitive to a signature quadratic in the field, then there is a dc component of the signal. Thus, a detector with a given finite bandwidth can be used to search for bosons with Compton frequencies many orders of magnitude larger than its bandwidth. Additionally, a search for such a signal would not require an accurate tunning to the unknown Compton frequency of the field. We show that existing optical magnetometers and atomic clocks networks have sufficient sensitivity to search experimentally unexplored parameter space using this scheme.

Speaker: Hector Masia Roig

GNOME_Interferometry_PATRAS2022.pdf

Talk_Patras2022_HMR.pdf

Talk_Patras2022_HMR.pptx

16:49 Search for Exotic Spin-Dependent Force with Atomic Comagnetometers

We report a new experimental result on searching for exotic spin- and velocity- dependent force using a tungsten nucleon source and an K-Rb-21Ne comagnetometer [1]. The pseudomagnetic field from this exotic force is measured to be ≤ 7 aT. This sets new limits on coupling constants for the neutron-nucleon and proton-nucleon interactions in the force range of ≥ 0.1 m.
[1] Wei, Kai, et al. arXiv:2203.07050 (2022).

Speaker: Wei Ji (Helmholtz Institut Mainz)

patras_WJ_poster55.pdf

16:52 Quantum Sensors for the Hidden Sector

In 2021 the Quantum Sensors for the Hidden Sector (QSHS) collaboration in the UK was founded and received funding to develop and demonstrate quantum devices with the potential to detect hidden sector particles primarily in the $\mu$eV to 100$\,\mu$eV mass window. The collaboration has been developing a range of devices and has started to develop a high-field, low-temperature facility at Sheffield University to characterise and test the devices in a haloscope geometry. Here, I introduce the QSHS collaboration aims and current progress.

Speaker: Ian Bailey (Lancaster University / Cockcroft Institute of Accelerator Science and Technology)

QSHSSlides_Patras2022_IBailey.pdf

16:55 Axion Haloscope Calibration from Reciprocity

Axion haloscopes intend to detect axions from the galactic halo. In the absence of detection, they constrain axion parameters like mass and coupling strength. Doing so requires a precise estimate of the expected axion signal power. The expected signal power in turn depends on the axion-induced electromagnetic field which, without detection, cannot be measured. Experiments thus depend heavily on simulations in order to constrain the axion parameter space. However, in the effort to push for higher axion masses, experiments become increasingly more complex and difficult, if not impossible, to fully simulate. It is therefore indispensable to verify the expected axion signal power in terms of measurable quantities allowing to calibrate more complex setups.

A lot of haloscopes have the ability to excite their system from the outside in order to estimate experimental parameters. In this scenario, the electromagnetic field is in principle measurable but generally different from the axion-induced field. The Lorentz reciprocity theorem, however, precisely relates these two scenarios.

In this talk, I will show how reciprocity yields an elegant expression for the axion signal power that for a set of well-motivated assumptions only depends on measurable electromagnetic fields and axion parameters. It applies to a wide variety of possible haloscopes and potentially provides a common description of formerly distinct setups. Furthermore, I will present possible ways to constrain the relevant electromagnetic fields, again applicable to a variety of setups.

Speaker: Jacob Egge (University of Hamburg)

axion_calibration_from_reciprocity_lightning_talk.pdf

16:58 Atomic spectroscopy setup to search for fundamental constant oscillations in a frequency range up to 125 MHz with a Hz resolution

The presence of ultralight dark matter particles could lead to a fundamental constant oscillation according to the models [See refs. in 1]. This oscillation could be detected using atomic and molecular spectroscopy techniques [2, 3]. In this work, we present a Cs Doppler-free spectroscopy apparatus for searching for the fundamental constant oscillation in a range of 20 kHz-125 MHz, which corresponds to the particle mass range 8x10-11 to 3x10-7 eV. Using a graphics card to perform a power spectral density calculation in parallel to the data acquisition process allows having a continuous, 100% duty cycle measurement with an ultimate sensitivity and frequency resolution better than 1 Hz. This setup gives us three order of magnitude better constraints on the dark matter to the electron mass and the fine-structure constant coupling than in the earlier work [2]. [1] M. G. Kozlov, D. Budker, Annalen Der Physik 2019, 531, 1800254. [2] D. Antypas et al., Phys. Rev. Lett. 123, 2019 [3] R. Oswald et al., arXiv:2111.06883

Speaker: Oleg Tretiak

patras poster 58 tretiak oleg.pdf

17:01 Search for Axion Stars Using the Global Network of Optical Magnetometers for Exotic Physics (GNOME)

Since the discovery of dark matter in our universe, numerous possible candidates have been proposed to explain its existence and composition. One of the candidates is the Ultralight axion-like particles, existing in the form of domain walls or axion stars, caused by topology or self-interactions. The Global Network of Optical Magnetometers to search for Exotic Physics (GNOME) looks for a transient signal caused by exotic-spin couplings as the Earth passes through such composite dark matter objects. We describe an analysis method for the GNOME data that is sensitive to axion stars based on the excess power technique.

*Supported by NSF Award PHY-1707803, PHY-2110370, PHY-1707875, PHY-2110388, PHY-2110385.

Speaker: Dhruv Tandon (Oberlin)

patras poster- Dhruv Tandon.pdf

patras poster- Dhruv Tandon.pptx

17:10 → 17:20 EU COST Action announcement

Convener: Kristof Schmieden (JGU Mainz)

17:10 EU COST Action announcement

Speaker: Axel Lindner

COST_presentation.pdf

17:20 → 17:30 Conference group picture

17:30 → 19:00 Poster Session: II

Wednesday 10 August

09:00 → 09:40 Invited talk: III

Convener: Fritz Caspers (cern)

09:00 Overview of ultralight scalar and vector dark matter searches - REMOTE

Abstract TBA

Speaker: Swati Singh

PatrasAug22.pdf

09:40 → 10:40 Contributed talks: V

Convener: Fritz Caspers (cern)

09:40 Planetary relationships as the new signature in astroparticle physics

The discovery of dunkle Materie (DM) by ZWICKY came from unexpected cosmological
observations. Similarly, the last ~160 years a number of unexpected energetic observations could be
the manifestation of the dark Universe. We refer to this class of particle candidates as “invisible” to
distinguish them from the already excluded parameter phase space of WIMPs and axions. In this
work we stress a simple feature as the common signature of such observations within the solar
system. Namely, the widely discussed dark sector constituents with velocity of ~1‰ c (c=velocity of
light). As pointed out since 20 years, streams of constituents with such velocities can be gravitationally
focused or deflected by any solar system body to others. The aforementioned energetic observations
include the unpredictable flaring Sun, its irradiance, its size variation, its elemental composition, etc,
but also terrestrial phenomena including the dynamic atmosphere and other highly crossdisciplinary
observations like the not randomly appearing Earthquakes. All observations follow otherwise
unexpected planetary relationships. More results may come out until this conference following more
out-of-the-box thinking including exo-solar planetary systems. To conclude, a planetary relationship
is a key signature pointing on its own at exo-solar origin. Also for Earthquakes, the only viable
explanation is thanks to planetary gravitational focusing of streaming invisible matter, which is
tentatively identified with constituents from the dark Universe, interacting with large cross section
with ordinary matter. Implications in (ongoing) DM experiments will be discussed. The mostly inspiring
particle constituents fitting-in a number of observations are AntiQuarkNuggets, magnetic monopoles
and dark photons. Though, more emerging candidates like the pearls (see work by Holger Nielsen)
are encouraged to investigate whether they fit-in, and, how to identify their possible involvement by
triggering energetic phenomena; so far, the solar radius variation is the most energetic observation.

Speaker: Prof. Konstantin Zioutas (University of Patras)

PATRAS 2022 TBPresented K.Z..pptx

10:00 Quark Nugget Dark Matter: hunter’s guide

Dark matter particles may be represented by compact composite objects of quark matter with macroscopic parameters of mass, charge and effective temperature. Such particles remain cosmologically and observationally dark if they possess a small cross section to mass ratio. A new feature of the Quark Nugget dark matter model is the prediction of existence of anti-quark nuggets (anti-QNs) built of antimatter and, thus, strongly interacting with visible matter. We study various types of radiation which such anti-QNs can produce, including thermal radiation and gamma photons from matter-antimatter annihilation. Assuming that these particles constitute the dominant dark matter fraction in our galaxy, we then estimate their radiation in our galaxy and compare it with various satellite and terrestrial observations. New detection approaches of this type of dark matter are proposed.

Speaker: Igor Samsonov (University of New South Wales)

Talk-quarknuggets.pptx

10:20 Latest results on dark matter axions with CAST-CAPP

Following a suggestion from 2012, the CAST experiment has been converted from an axion helioscope to an axion haloscope searching for Dark Matter axions. The CAST-CAPP sub-detector whose results will be presented consists of four tunable microwave cavities with no mode crossings for the axion mode, situated inside one of the two twin bores of the CAST dipole magnet. For the first time in axion research, the detector uses the phase-matching technique that improves the signal-to-noise ratio and a novel fast-tuning mechanism that allows searching for transient events. The excluded frequency range for galactic axions extends over a frequency range of ~660 MHz, i.e., axions with masses around 19.74 – 22.47 μeV and sets a competitive limit.

Speaker: Marios Maroudas (University of Patras)

2022_08_10 - Patras Workshop Presentation.pptx

10:40 → 11:10 Coffee

11:10 → 12:30 Contributed talks: VI

Convener: Wolfgang Funk (CERN)

11:10 LZ status

LUX-ZEPLIN (LZ) is a dark matter direct detection experiment located at the Sanford Underground Research Facility in Lead, South Dakota. At the heart of the detector is a dual-phase time projection chamber containing 7 tonnes of active liquid xenon. During its 1000-day science run, LZ aims to achieve unprecedented sensitivity to Weakly Interacting Massive Particles (WIMPs) down to a WIMP-nucleon spin-independent cross section of about $1.4 \times 10^{-48} \text{cm}^{2}$ for a $40 \text{GeV}/\text{c}^{2}$ mass WIMP. In this talk, I will give an overview of the LZ experiment and report on its status and performance during its first science run.

Speaker: Theresa Fruth (UCL)

LZstatus_PATRAS_TheresaFruth 3.pdf

11:30 Status update of the axion helioscope BabyIAXO

The International Axion Observatory (IAXO) is a large-scale axion helioscope that will look for axions and axion-like particles (ALPs) produced in the Sun. It is conceived to reach a sensitivity on the axion photon coupling in the range of $10^{−12}\,\text{GeV}^{−1}$.
On the way to IAXO, an intermediate experiment BabyIAXO is already in the construction phase. BabyIAXO will be important to test all IAXO subsystems (magnet, optics and detectors) and at the same time, as a fully-fledged helioscope, will reach a sensitivity on the axion-photon coupling of $1.5\times 10^{−11}\,\text{GeV}^{−1}$ for masses up to 0.25 eV, covering a very interesting region of the parameter space.
Important milestones have been reached in the past years in the development of the different components of the experiment as low background X-ray detectors and X-ray optics as well as for the design of the large magnet hosting two 10 m long bores with a diameter of 0.7 m for axion to photon conversion. The design of the mechanical infrastructures allowing for a Sun monitoring during half of a day has been defined.
We report on the recent characterisation of BabyIAXO subsystems and discuss how the achieved results compare to the requirements. We finally discuss the schedule for the construction of the BabyIAXO helioscope.

Speaker: Tobias Schiffer (University of Bonn (DE))

IAXO_Patras1.pdf

11:50 BREAD: Broadband Reflector Experiment for Axion Detection - Towards GHz and Infrared Pilot Experiments

BREAD is a novel dish antenna for broadband ~$\mu$eV-eV axion and wave-dark matter detection, which allows to utilize state-of-the-art high-field solenoidal magnets. Axions are converted non-resonantly to photons on a cylindrical metallic wall parallel to an external magnetic field. These photons are then focused using a novel reflector geometry onto a state-of-the-art high-sensitive photon detector. We recently demonstrated [PRL 128 (2022) 131801] that this concept using a $\sim 10\,{\rm m}^2$ conversion area in a $\sim 10\,{\rm T}$ solenoidal magnet has the potential to discover QCD axions spanning multiple decades in mass range. In this talk we will also show progress towards first stage hidden photon and axion pilot experiments for two distinct frequency ranges - GigaBREAD and InfraBREAD - with expected sensitivities to unexplored coupling strengths. We detail R&D on reflector characterization, horn antenna & sensor testing and signal readout. We also outline sensitivity estimates for future large-scale versions.

Speaker: Stefan Knirck (Fermi National Accelerator Laboratory)

knirck_stefan_bread_patras.pptx

12:10 The quantum limits on magnetic resonance searches for axion-like dark matter

Magnetic resonance is a versatile tool for searching for axion-like dark matter. CASPEr is one example of this approach. I will focus on the quantum limits on the sensitivity of magnetic-resonance-based searches, emphasizing the importance of evading back action on the spin ensemble from the sensor used to detect its dynamics [1]. I will also discuss schemes that have potential for achieving sensitivity beyond the spin projection noise limit, and their experimental feasibility.

[1] Aybas, D., Bekker, H., Blanchard, J., Budker, D., Centers, G., Figueroa, N., Gramolin, A., Kimball, D. F., Wickenbrock, A., Sushkov, A. O., “Quantum Sensitivity Limits of Nuclear Magnetic Resonance Experiments Searching for New Fundamental Physics.” Quantum Science and Technology 6(3), 034007 (2021).

Speaker: Alex Sushkov (Boston University)

2022-08-10 TALK PATRAS CASPEr.pptx

12:30 → 12:32 Annalen der Physik Special Issue announcement

12:30 Annalen der Physik Special Issue announcement

Speakers: Arne Wickenbrock, Dmitry Budker

Call_for_Papers_Wavy_Dark_Matter_15nov.pdf

Dark_matter_SI_AdP_Patras.pptx.pdf

12:32 → 14:00 Lunch

14:00 → 19:00 Social Events: Excursion

19:00 → 22:00 Social Events: Conference Dinner

Thursday 11 August

09:00 → 09:40 Invited talk: IV

Convener: Abaz Kryemadhi (Messiah University)

09:00 HF Gravitational Waves searched by Axion Experiments

Plenary on HF Gravitational Waves searched by Axion Experiments

Speaker: Camilo Garcia Cely

PatrasCamiloGarciaCely.pdf

09:40 → 10:40 Contributed talks: VII

Convener: Abaz Kryemadhi (Messiah University)

09:40 Progress on the Axion Resonant InterAction Detection Experiment (ARIADNE) - REMOTE

The Axion Resonant InterAction Detection Experiment (ARIADNE) is a “fifth-force” experiment that can search for the QCD axion in the mass range of 10 micro-eV to 10 meV via its coupling to nucleons. In the setup, the QCD axion mediates a novel short-range spin-dependent interaction between an unpolarized tungsten source mass and laser-polarized 3He nuclei, that can be detected via nuclear magnetic resonance. By sourcing virtual axions locally, the approach is independent of cosmological assumptions, and unlike axion haloscopes, does not involve scanning over axion frequencies. The experiment requires a low-vibration non-magnetic liquid helium cryostat, superconducting shielding to limit ordinary magnetic noise, and a stable rotary system to modulate the axion-signal from the source mass. In this talk I will discuss the testing, characterization, and commissioning of several key components of the experimental apparatus and describe the next steps for bringing the experiment into its early data taking phase. When taken together with other existing and planned axion efforts, ARIADNE and other searches have the potential to discover the QCD axion over its entire allowed mass range.

Speaker: Andrew Geraci (Northwestern University)

PATRAS2022_ARIADNE.pdf

PATRAS2022_ARIADNE.pptx

10:00 Advances in searching for galactic axions with a Dielectric Haloscope (MADMAX)

Axions are hypothetical particles that could explain the observed dark matter density and simultaneously, they can naturally resolve the strong CP problem in QCD. Recent theoretical works indicate that axions are expected to have masses in the range of 40-400 μeV, a range that presently still evades experimental sensitivity.
We present a new experimental design to search for QCD axions in this mass range via the MAgnetised Disk and Mirror Axion eXperiment (MADMAX). MADMAX will be composed of multiple movable dielectric disks and a mirror that are placed inside a strong magnetic field to utilize the axion-induced coherent electromagnetic wave emissions from each disc surface.
In this contribution, the basic concept of MADMAX will be introduced and laboratory-based setups investigating the feasibility of the experiment will be shown. First measurements from a small down-scaled dielectric haloscope performed inside the MORPUGO magnet at CERN will be discussed.

Speaker: Antonios Gardikiotis (Universität Hamburg)

Patras_2022_MADMAX.pdf

Patras_2022_MADMAX.pptx

10:20 A Visible QCD Axion Explanation of the XENON1T Excess and of (g-2)𝜇

The XENON1T excess in electron recoils can be fit by non-relativistic Dark Matter (DM) interactions mediated by a light pseudo-scalar in the MeV range. A tantalizing option for the pseudo-scalar mediator is the QCD axion that, in the mass range of a few MeV, is generally known as a “visible” axion. In our work we consider axion models with flavor non-universal couplings to Standard Model (SM) fermions, such that the resulting axion is pion-phobic and is able to evade a variety of very stringent phenomenological bounds (quarkonia decays, kaon decays and electron beam dump experiments). We study, in a model independent way, the complex phenomenology of this class of models and we also find that the Anomalous Magnetic Moments for both the electron and muon can be simultaneously explained. We finally construct a possible UV DFSZ-like model that is able to generate flavor non-universal couplings to SM fermions of the required size, and at the same time, to make the axion a portal to a Dark Sector. One of the consequences of this construction is to generate additional couplings and therefore enrich the already interesting phenomenology of the model. Specifically, we find that the unavoidable couplings of DM with light quarks and gluons induces elastic DM-nucleus collisions that, by using the XENON1T nuclear recoils, further constrains the parameter space.

Speaker: Mr Giovanni Armando (University of Pisa and INFN)

giovanni_armando_slides.pdf

10:40 → 11:10 Coffee

11:10 → 12:30 Contributed talks: VIII

Convener: Sebastian Schenk (IPPP Durham)

11:10 T-RAX: Transversely Resonant Axion eXperiment

We propose to use an elongated rectangular waveguide near its cutoff frequency for axionic dark matter searches. The detector's large surface area allows for significant signal power, while its narrow transverse dimension and tapered-waveguide coupling suppress parasitic modes. The proposed system can fit inside a solenoid magnet and is sensitive to the QCD-axion in the axion mass $40-400\,\mu$eV. We describe the theoretical principles of the new design, present simulation results, and discuss the implementation. We conclude by discussing the application of a single-photon counter.

Speaker: Chang Lee (Max Planck Institute for Physics)

PATRAS_T_RAX_CLEE.pdf

11:30 Probing the axion gradient-coupling with nuclear magnetic resonance spectroscopy

The cosmic axion spin precession experiment (CASPEr) is a nuclear magnetic resonance (NMR) experiment to search for axion and axion-like particles (ALPs) [1]. With the CASPEr-Gradient setups in Mainz we aim to probe the coupling of nuclear spins to the gradient of the ALP field for the mass range of approximately 10^-13 to 10^-6 eV, corresponding to the Compton frequency range of 100 Hz to 600 MHz. In this presentation, we describe the two setups and the considerations that have led to the current design, followed by a status update and outlook. These will all be related to our recent work on sensitivity limits of NMR [2], spectral signatures of the ALP signal [3], and stochastic properties of the ALP field [4].

[1] D.F. Jackson Kimball, et al. “Overview of the Cosmic Axion Spin Precession Experiment (CASPEr).” In Microwave Cavities and Detectors for Axion Research, edited by Gianpaolo Carosi and Gray Rybka, 105–21. Springer Proceedings in Physics. Cham: Springer International Publishing, 2020.
[2] D. Aybas, et al. “Quantum Sensitivity Limits of Nuclear Magnetic Resonance Experiments Searching for New Fundamental Physics.” Quantum Science and Technology 6, no. 3 (June 15, 2021): 034007.
[3] A.V. Gramolin, et al. “Spectral Signatures of Axionlike Dark Matter.” Physical Review D 105, no. 3 (February 24, 2022): 035029.
[4] G.P. Centers, et al. “Stochastic Fluctuations of Bosonic Dark Matter.” Nature Communications 12, no. 1 (December 16, 2021): 7321.

Speaker: Hendrik Bekker (HIM)

CASPEr-gradient LF.pptx

11:50 Searching for Wavelike Dark Matter with SRF Cavities

Haloscopes consisting of a microwave cavity with a high quality factor (Q) connected to low noise electronics have been deployed to detect wavelike axions and dark photons. But the dark matter mass is unknown, so haloscopes must be tunable to search through the photon coupling vs. mass parameter space. Therefore, the scan rate for haloscope experiments is a crucial figure of merit and is proportional to the cavity’s quality factor. State-of-the-art experiments like ADMX currently use copper cavities with $Q\sim 80000$. However, implementing superconducting cavities with $Q\sim 10^{10}$ can increase the scan rate by possibly a factor of $10^5$.

This presentation will discuss the principles behind operating a haloscope whose bandwidth is much narrower than the dark matter halo energy distribution. I will then discuss proof-of-principle measurements that demonstrate that ultra-high Q cavities have unprecedented sensitivity to dark photon dark matter. Next, I will discuss plans to commission a dark photon dark matter search over a wide frequency range. Finally, I will discuss the applications of ultra-high Q cavities for axion searches and progress toward realizing ultra-high Q cavities under multi-Tesla magnetic fields.

Speaker: Raphael Cervantes (Fermilab)

patras2022_RaphaelCervantes.pdf

12:10 First results of the DOSUE-RR experiment - search for dark photon CDM in the mass range $74 - 110~\mu{\rm eV}/c^2$

Dark photon cold dark matter (CDM) is one of the WISPs. Dark-matter Observing System for Un-Explored Radio-Range (DOSUE-RR) is a series of experiments to search for the dark photon CDM using millimeter-wave spectroscopy. The dark photons convert to ordinary photons at the boundary of electromagnetic fields such as a metal surface. The frequency of the conversion photon corresponds to the mass of the dark photon CDM owing to the energy conservation, i.e., $h\nu \simeq mc^2$. We aim to detect the signal in the frequency spectrum.

For the first experiment, we developed a cryogenic millimeter-wave receiver in a frequency range $18 - 26.5~{\rm GHz}$, which corresponds to a dark photon mass range $74 - 110~\mu{\rm eV}/c^2$. Our first search was performed for two weeks in 2021. We found no signal of the dark photon CDM, and set an upper limit on the coupling constant between dark photons and ordinary photons: $\chi < (0.3 - 2.0) \times 10^{-10}$ at 95\% confidence level. This is the most stringent constraint to date, and tighter than indirect constraints from cosmological observations. In this workshop, we will present our first results and future prospects.

https://arxiv.org/abs/2205.03679

Speaker: Osamu Tajima (Kyoto University)

2022_0811_DOSUE_K_tajimao.pptx

12:30 → 14:00 Lunch

14:00 → 14:30 Long talk: V

Convener: Gray Rybka (U. of Washington)

14:00 Dark Matter Radio Cubic Meter

The QCD axion, originally proposed as a solution to the strong CP problem in QCD, is one of the most strongly motivated candidates for dark matter. In this talk, I will describe a suite of experiments referred to as the Dark Matter Radio that search for the coupling of axionic dark matter to electromagnetism at masses below 1 $\mu$eV. Axions at these lower mass ranges can naturally be produced in the measured dark matter abundance if Peccei-Quinn symmetry breaking occurs prior to inflation. A particularly well motivated mass range is from 1-100 neV, which corresponds to PQ symmetry breaking near the Grand Unified Theory (GUT) scale. At these lower frequencies, the Compton wavelength is typically larger than the experimental dimension, so the resonators used are similar to lumped-element resonators. This talk will present an overview and status update of the design of the Dark Matter Radio Cubic Meter (DMRadio-m$^3$) experiment and briefly review plans for a next-generation GUT-scale-sensitive experiment, DMRadio-GUT. Both DMRadio-m$^3$ and DMRadio-GUT are sensitive to the DFSZ axion model.

The DMRadio collaboration is funded by DOE, NSF, the Gordon and Betty Moore Foundation, and the Heising-Simons Foundation. DMRadio-m$^3$ is supported by DOE under the Dark Matter New Initiatives (DMNI) program.

Speaker: Maria Simanovskaia (Stanford University)

Dark Matter Radio - Cubic Meter_final.pdf

14:30 → 15:10 Contributed talks: IX

Convener: Gray Rybka (U. of Washington)

14:30 Status of the QUAX experiment

The QUest for Axion (QUAX) is a direct-detection CDM axion search which reaches the sensitivity necessary for the detection of galactic QCD-axion in the range of frequency 8.5-11 GHz. The QUAX collaboration is operating two haloscopes, located at LNL- and LNF-INFN laboratories in Italy, that work in synergy and operate in different mass ranges. In this talk we will report about the LNL haloscope, currently talking data at 10.3 GHz with a dielectric resonator cooled at less than 100mK inside a dilution refrigerator equipped with a 8 T magnet. In addition, the system noise is minimised in the wide frequency range where the cavity can be tuned by means of a new generation traveling wave parametric amplifier (TWPA) developed by the group of N. Roch (Grenoble), with measured noise temperature of 2 K or better. We will describe the results of preliminary runs, where a narrow range tuning system (1 MHz) was employed. Data sets were acquired with significantly different antenna couplings, to investigate the experimental requirements that are needed for running the experiment with a cavity exceeding the axion quality factor.
We will also report about R&D activity aimed at increasing the scanning speed with application of single microwave photon detectors (SMPDs) for cavity readout, in collaboration with E. Flurin (Quantronics, Saclay). The prototype haloscope is based on a cylindrical copper cavity sputtered with NbTi, with a quality factor of 5 10^5 at 5 K and the experiments will be conducted at 7 GHz frequency in a dilution refrigerator where a moderate magnetic field (3T) can be applied. Systematic studies of the SMPD dark count and efficiency will be described.

Speaker: Caterina Braggio (University of Padova and INFN)

QUAX_PUBLISH.pdf

14:50 New Axion Dark Matter Search Techniques

We will present new ideas and research programs underway at UWA related to searching for axion dark matter over various mass ranges. This includes but is not limited to the following:

1) We have realised a new class of photonic microwave cavity resonators, which exhibit modes of anyon symmetry. The cavity resonators exhibit monochromatic modes with non-zero helicity. We implement Poynting theorem and show that such modes will have enhanced coupling to low-mass axions, this manifest through the axion modifications to Maxwell’s equations adding electromagnetic chirality.

2) We use Poynting theorem to analyze the power and frequency upconversion techniques in the AC haloscope. Such haloscopes necessarily implement two modes in one resonator. We highlight some new advantages over the DC haloscopes that this technique offers when putting limits on axion couplings.

3) We discuss the sensitivity of lumped element detectors through the use of Poynting theorem.

4) It is also now known that dark matter axion haloscopes that operate to detect axions via the two-photon anomaly are also sensitive to gravitation radiation through the inverse Gertsenshtein effect. We discuss how our experimental program may be modified to allow the search for gravitational waves at high frequencies.

Speaker: Michael Tobar (University of Western Australia)

Patras22_MET.pdf

15:10 → 15:40 Coffee

15:40 → 16:10 Long talk: VI

Convener: Felix Yu (JGU Mainz)

15:40 Cosmological constraints on decaying axion-like particles: a global analysis

Future cosmological probes promise significant progress in probing the dark universe and the related fundamental particles. Their impact is most powerful when we combine cosmological data with astrophysical observations and laboratory experiments. While computational tools are available for such studies, the large number of model parameters and ensuring consistency between data sets can present difficult challenges.
In this talk, I will show how the global-fitting framework GAMBIT can be used to constrain non-thermal axion-like particles (ALPs) with keV-to-MeV masses that decay into photons [arXiv:2205.13549]. For the first time we combine various cosmological and astrophysical constraints in a joint likelihood approach. This ensures the consistency of assumptions and allows us to investigate the entire multi-dimensional parameter space instead of fixing some parameters to benchmark values.
Leaving the ALP abundance and reheating temperature as free parameters, we identify and re-open still viable ALP parameter space – even slightly improving BBN observables compared to standard cosmology. In this context, I will comment on the additional constraining power from future spectral distortion missions. Our findings demonstrate the important complementarity of astrophysical and cosmological data and encourage the extension of our analysis to models with ALP-matter couplings.

Speaker: Sebastian Hoof (Georg-August-Universität Göttingen)

2022_patras_mainz.pdf

16:10 → 17:10 Contributed talks: X

Convener: Felix Yu (JGU Mainz)

16:10 The fat tails of axion-photon mixing

One of the most powerful probes of axion-like particles (ALPs) comes from considering their mixing with photons in large-scale astrophysical magnetic fields, e.g. in galaxy clusters. However, such searches requires modelling the magnetic field, which is only in part constrainable by observations. In this talk, I will address the questions of how sensitive the ALP predictions are to the magnetic field modelling. In particular, large coherent structures are expected from both magnetohydrodynamic simulations (MHD) and astronomical observations, but absent from the simpler models used so far in the literature. How do coherent structures affect the conversion probability of ALPs and photons? I will present new results based on the first systematic study of ALP-photon mixing in MHD magnetic fields, and compare these with other models used in the literature. An important finding is that the magnetic non-Gaussianity of MHD models leads to ‟fat tails” in the distribution of conversion probabilities. This result could improve the prospects of high-precision searches of ALPs, and suggests that limits placed using appropriate, simple models are conservative and robust.

Speaker: M.C. David Marsh (Stockholm University)

Patras 22-Marsh-upload.pdf

16:30 Updated Results from HAYSTAC's Quantum-Enhanced Search for Dark Matter Axions - REMOTE

The HAYSTAC Collaboration is currently searching for axion cold dark matter with the use of a resonant microwave cavity. Because both the mass of the axion and its coupling strength are largely unknown, a key figure of merit for a haloscope is the rate at which it can scan this vast parameter space. Recent progress in developing squeezed state receivers have allowed HAYSTAC to reduce noise levels below the standard quantum limit, resulting in a factor of two scan rate enhancement as first demonstrated in the search over the combined axion mass window of 16.96-17.12$\mu$eV and 17.14-17.28 $\mu$eV. This quantum enhanced search was continued between July and September 2021, extending the scanned region to axions with masses between 18.45-18.69$\mu$eV. In this update, I will discuss the status of HAYSTAC with emphasis on the most recent data taking phase that includes improvements to the data acquisition routine which have reduced dead time by a factor of two, further improving the scan rate of the experiment.

Speaker: Dr Michael Jewell (Yale)

haystac_jewell_patras_2022_v2.pdf

16:50 The Sensitivity of Spin-Precession Axion Experiments

Spin-precession experiments are the leading efforts to detect axion dark matter interacting with nuclei. The experimental strategy is to polarize the nuclear spin in one direction with a background magnetic field and search for spin-precession induced by the oscillating axion field using a sensitive magnetometer. I revisit the experimental strategy over all hierarchies between the relevant time scales: the axion coherence time, the integration time, and the spin-relaxation time. The calculation reveals new features in how the axion interacts with nuclear magnetic resonance experiments. The results are applicable to searches for the axion coupling to nucleons, and also the coupling to gluons, which would be responsible for solving the strong CP problem.

Speaker: Jacob Leedom (DESY)

JML_NMR_PATRAS_2022.pdf

Friday 12 August

09:00 → 10:40 Contributed talks: XI

Convener: Caterina Braggio (University of Padova and INFN)

09:00 ADMX results

The QCD axion arises from the Peccei-Quinn solution to the Strong CP problem and is a compelling dark matter candidate. Interest in the axion and other wavelike dark matter candidates has grown recently, yielding both new theoretical perspectives and new refinements in detection technology. The Axion Dark Matter Experiment is currently searching for dark matter axions with sensitivity to some of the best-motivated parameter space. I will report recent results from ADMX and future run plans specifically, and more generally give a brief report on the discussions of the "Wavelike Dark Matter Working Group" from the US Snowmass process.

Speaker: Gray Rybka (U. of Washington)

2022_rybka_patras.pdf

09:20 Radiometric broadband searches for light dark matter with BRASS-p

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Broadband Radiometric Axion SearcheS (BRASS) is the haloscope experimental framework that can be employed to search for the axion/ALPs and hidden photons by employing novel experimental approaches and synergies with state-of-the-art broadband techniques developed in radio astronomy.

The prototype, BRASS-p - developed at the University of Hamburg, is a broadband detector that searches for light dark matter signal in the frequency range of 12-18 GHz. This talk will discuss the setup and calibration of BRASS-p, which comprises the conversion panel, parabolic mirror, cryogenic broadband receiver, and digital backend system. We present our signal scan routine of the first science run targeting the hidden photon dark matter within 12-18 GHz, and discuss the preliminary result from the first science run.

Speaker: Le Hoang Nguyen (Hamburg Universität)

BRASS-p Le Hoang Nguyen.pdf

compressed_slide_not_for_talk.pdf

09:40 Status and new results of the CRESST Experiment

The CRESST-III (Cryogenic Rare Event Search with Superconducting Thermometers) experiment is looking for the direct detection of dark matter particles via their scattering off target nuclei in cryogenic detectors, operated at mK temperatures. Energy thresholds of less than 100 eV allow for the search of sub-GeV dark matter masses, making CRESST one of the leading experiments in low-mass DM searches. At low energies (< 200 eV) an unexpected rise of events is observed, limiting the sensitivity of CRESST. The current data-taking campaign is fully dedicated to study the origin of this "Low Energy Excess" (LEE). We present an overview of the CRESST-III experiment and report on both, new DM results and recent observations concerning the LEE. Furthermore, we give an update on R&D and plans for the CRESST upgrade.

Speaker: Dominik Fuchs

CRESST_PATRAS2022.pdf

10:00 Bounds on diffuse supernova axion flux with $Fermi$-LAT

Axion-like particles (ALPs) may be abundantly produced in core-collapse (CC) supernovae (SNe), hence the cumulative signal from all past SN events can create a diffuse flux peaked at energies of about 25~MeV.
We improve upon the modeling of the ALPs flux by including a set of CC SN models with different progenitor masses, as well as the effects of failed CC SNe -- which yield the formation of black holes instead of explosions. Relying on the coupling strength of ALPs to photons and the related Primakoff process, the diffuse SN ALP flux is converted into gamma rays while traversing the magnetic field of the Milky Way. The spatial morphology of this signal is expected to follow the shape of the Galactic magnetic field lines.
We make use of this via a template-based analysis that utilizes 12 years of Fermi-LAT data in the energy range from 50 MeV to 500 GeV. In our benchmark case of the realization of astrophysical and cosmological parameters, we find an upper limit of $g_{a\gamma} \lesssim 3.76\times10^{-11}\;\mathrm{GeV}^{-1}$ at 95$\%$ confidence level for $m_a \ll 10^{-11}$ eV, while we find that systematic deviations from this benchmark scenario induce an uncertainty as large as about a factor of two.\
Talk based on F. Calore $et$ $al$, "3D template-based $Fermi$-LAT constraints on the diffuse supernova axion-like particle background".

Speaker: Francesco Sivo (INFN)

Presentation_Francesco_Sivo.ppsx

10:20 Electromagnetic couplings of axions

We show that, contrary to assertions in the literature, the main contribution to the axion-photon coupling need not be quantized in the units proportional to $e^2$. In particular, we discuss a loophole in the argument for this quantization and then provide explicit counterexamples. Hence, we construct a generic axion-photon effective Lagrangian and find that the axion-photon coupling may be dominated by previously unknown Wilson coefficients. We show that this result implies a significant modification of conventional axion electrodynamics and sets new targets for axion experiments. At the core of our theoretical analysis lies a critical reexamination of the interactions between axions and magnetic monopoles. We show that, contrary to claims in the literature, magnetic monopoles need not give mass to axions. Moreover, we find that a future detection of an axion or axion-like particle with certain parameters can serve as evidence for the existence of magnetically charged matter.

Speaker: Anton Sokolov (Deutsches Elektronen-Synchrotron DESY)

Sokolov_PATRAS2022.pdf

10:40 → 11:10 Coffee

11:10 → 12:10 Contributed talks: XII

Convener: Georg Raffelt (MPP Munich and LMU Munich)

11:10 DARWIN Status

DARWIN Status

Speaker: Adam Brown

patras22adambrown.pdf

11:30 Constraining Warm Dark Matter and Pop III stars with the Global 21-cm Signal

Upcoming ground and space-based experiments may have sufficient accuracy to place significant constraints upon high-redshift star formation, Reionization, and dark matter (DM) using the global 21-cm signal of the intergalactic medium. In the early universe, when the relative abundance of low-mass DM halos is important, measuring the global signal would place constraints on the damping of structure formation caused by DM having a higher relic velocity (warm dark matter, or WDM) than in cold dark matter (CDM). Such damping, however, can be mimicked by altering the star formation efficiency (SFE) and difficult to detect because of the presence of Pop III stars with unknown properties. We study these various cases and their degeneracies with the WDM mass parameter mX using a Fisher matrix analysis. We study the mX=7 keV case and a star-formation model that parametrizes the SFE as a strong function of halo mass and include several variations of this model along with three different input noise levels for the likelihood; we also use a minimum halo virial temperature for collapse near the molecular cooling threshold. We find that when the likelihood includes only Pop II stars, mX is constrained to an uncertainty of ∼0.4 keV for all models and noise levels at 68% CI. When the likelihood includes weak Pop III stars, mX∼0.3 keV, and if Pop III star formation is relatively efficient, mX∼0.1 keV uncertainty, with tight Pop III star-formation parameter constraints. Our results show that the global 21-cm signal is a promising test-bed for WDM models, even in the presence of strong degeneracies with astrophysical parameters.

Speaker: Joshua Hibbard (Astrophysical and Planetary Sciences Department, University of Colorado Boulder)

17th PATRAS Workshop.pdf

17th PATRAS Workshop.pptx

11:50 Friendship in the Axiverse

A generic low-energy prediction of string theory is the existence of a large collection of axions commonly known as a string axiverse. In a realistic axiverse, string axions can be distributed densely over many orders of magnitude of mass, and are expected to interact with one another through a joint potential. I will show that non-linearities in this potential lead to a new type of resonant energy transfer between axions with nearby masses. This resonance is not captured by linearized treatments previously discussed in the literature, and generically results in a transfer of energy density from axions with larger decay constants to those with smaller decay constants, leading to a multitude of late-time signatures. These include enhanced direct detection prospects for a resonant pair comprising even a small subcomponent of dark matter (DM), and boosted small-scale structure if the pair is the majority of DM. Near-future iterations of experiments such as ADMX and DM Radio will be sensitive to this scenario, as will astrophysical probes of DM substructure.

Speaker: Jedidiah Thompson (Stanford University)

FriendshipInTheAxiverse.pdf

12:10 → 12:30 Organizers: Poster Prizes and Closeout

Convener: Arne Wickenbrock

12:30 → 14:00 Lunch