Conveners
Low Energy Nucleon Structure
- Edoardo Mornacchi
Low Energy Nucleon Structure
- Vladimir Pascalutsa (JGU Mainz)
The High Intensity Gamma-Ray Source (HIGS) at Duke University delivers monoenergetic photon beams with high linear or circular polarization by backscattering of free-electron laser (FEL) photons [1]. To exploit the unique capabilities of this facility, we are conducting an ambitious program of Compton scattering studies on light nuclei aimed at determining the nucleon electromagnetic...
A central problem of modern physics research is the solution to QCD in the non-perturbative regime. One method of testing QCD in this low-energy region is by measuring certain structure constants of hadrons - called polarizabilities - that show particular promise of allowing a direct connection to the underlying quark/gluon dynamics through comparison to modern QCD-inspired model...
The polarizabilities of a composite system such as the proton are elementary structure constants. They describe its response to an external electromagnetic (EM) field and quantify the deformation of the charge and magnetization distributions inside the proton caused by the electric or magnetic field, respectively. When studied through the virtual Compton scattering process, the virtuality of...
In few-nucleon systems, the transition-density formalism is highly efficient
to compute interactions with perturbative probes. One- and two-body
transition densities that encode the nuclear structure of the target are
evaluated once and stored for one nucleus. They are then convoluted with an
interaction kernel to produce observables. The same densities can be used with
different kernels....
We present results for the electromagnetic form factors of the proton and neutron computed on the $(2 + 1)$-flavor Coordinated Lattice Simulations (CLS) ensembles including both quark-connected and -disconnected contributions. The $Q^2$-, pion-mass, lattice-spacing, and finite-volume dependence of our form factor data is fitted simultaneously to the expressions resulting from covariant chiral...
The electromagnetic form factors (EMFFs) and the pair production cross sections of various baryons
have been studied at BESIII, including the nucleon EMFFs and the hyperons. Anomalous enhancement behavior
on the Lambda and Lambdac pair are observed. Besides, measurements on the SU(3) decuplet baryon have been
performed, such as Omega and Delta, and will be presented.
The nucleon self-energy is calculated in SU(2) covariant chiral perturbation theory to study the pion mass dependence of the nucleon mass up to chiral order $\mathcal{O}(q^6)$, i.e., including two-loop diagrams.
The contributions of the diagrams are expressed by a small set of (scalar) master integrals. The extended on-mass-shell (EOMS) renormalization scheme is applied, where (besides the...
The Bernabéu-Tarrach sum rule, the "virtual sibling" of the Baldin sum rule, will be discussed. It could potentially offer an additional data-driven constraint on the electric polarizabilities of the nucleon. Moreover, its convergence implies the sum rule for the unknown subtraction function in the two-photon exchange contribution to the Lamb shift. The verification of these sum rules will be...
