Title: Chiral partner contribution to sound velocity peak in dense two-color QCD
Date: Apr 22, 2024
Time: 10:30 - 11:30
Speaker: Dr. Mamiya Kawaguchi
Affiliation: University of Chinese Academy of Sciences
Abstract: The presence of a peak structure in the sound velocity is essential for reproducing the observation of the mass and radius relation in neutron stars. Recently, to clarify the presence of the sound velocity peak in baryonic dense systems, the chemical potential dependence of the sound velocity has been evaluated in a lattice simulation of two-color QCD, instead of the real-life QCD with three colors. The numerical result has indicated the appearance of the peak structure in the sound velocity. However, the chiral perturbation theory (ChPT), which serves as a low-energy effective model for the lightest hadrons, fails in reproducing the peak structure at finite quark chemical potential in the two-color QCD with two quark flavors.
In this talk, I will discuss the discrepancy in the sound velocity between the two-color QCD lattice observation and the low-energy effective model result. First, I will extend the ChPT results to incorporate excited hadrons into the low-energy effective theory by employing the linear sigma model which includes the sigma meson identified as the chiral partner of pions. Within the mean field approximation, I will address the extent to which the chiral partner contributes to the sound velocity peak. In addition, I will also discuss the chiral partner contribution to the trace anomaly in dense two-color QCD.