Speaker
Description
Chiral effective field theory ($\chi$EFT) is an approach to describe the force between nucleons as arising from the more fundamental principles of quantum chromodynamics. A vital part is to have a power counting (PC) that describes the relative importance of the EFT order-by-order contributions to nuclear observables. The definition of the PC is not unique, and the fact that nuclear systems are non-perturbative makes finding a proper PC a non-trivial problem. We have done a Bayesian analysis of a renormalization-group invariant PC at leading order (LO) [1], and we analyze the posterior probability density of the low-energy constants (LECs) for momentum cutoffs in the range 400 -- 4000 MeV. We find multi-modal posteriors for the LECs, some overly repulsive P-wave phase shifts, a decent LO description of scattering observables and a slight under-binding of the deuteron. In this PC corrections beyond LO are included perturbatively. Recent developments regarding the analysis of higher orders will also be presented.
[1] O. Thim, E. May, A. Ekström, C. Forssén, arXiv:2302.12624 (2023)
