Speaker
Description
Baryon interactions are one of the most fundamental quantities in nuclear physics. Their properties in vacuum have been extensively studied via scattering experiments and many theoretical methods. In medium, however, the baryon interactions are poorly examined, although they are indispensable to deepen our microscopic understanding on e.g. the structure of neutron stars and heavy-ion collision dynamics.
As a step toward the understanding of baryon interactions in medium, we analyze the baryon-baryon interactions at finite isospin chemical potential based on leading-order chiral Lagrangian. The Lagrangian possesses the isospin U(1) symmetry, spontaneously broken at the isospin larger than the pion mass. The resulting gapless phonon mediates the interaction between baryons. As in the case of polarons in superfluids [K. Fujii, M. Hongo, and T. Enss (2022)], the long-range part of the neutron-neutron interaction is described by a two-phonon exchange diagram and exhibits van der Waals-type scaling behavior. We will also discuss the baryon interactions including hyperons. Since the lattice QCD calculation can be performed at finite isospin chemical potential, this study provides a basis for reliably extending lattice QCD studies of baryon interactions to in-medium systems.