Chiral-spin symmetry of the meson spectral function above $T_c$

TL;DR

This study demonstrates that above the critical temperature, the meson spectral function exhibits chiral-spin and $SU(4)$ symmetries, indicating a regime where quarks are bound by chromoelectric fields into color singlets without chromomagnetic effects.

Contribution

It provides the first evidence that the meson spectral function above $T_c$ maintains chiral-spin and $SU(4)$ symmetries, supporting the Stringy Fluid model of QCD.

Findings

Meson spectral function is chiral-spin symmetric.

Spectral function exhibits $SU(4)$ symmetry.

Symmetries persist slightly above $T_c$.

Abstract

Recently, via calculation of spatial correlators of $J=0,1$ isovector operators using a chirally symmetric Dirac operator within $N_F=2$ QCD, it has been found that QCD at temperatures $T_c - 3 T_c$ is approximately $SU(2)_{CS}$ and $SU(4)$ symmetric. The latter symmetry suggests that the physical degrees of freedom are chirally symmetric quarks bound by the chromoelectric field into color singlet objects without chromomagnetic effects. This regime of QCD has been referred to as a Stringy Fluid. Here we calculate correlators for propagation in time direction at a temperature slightly above $T_c$ and find the same approximate symmetries. This means that the meson spectral function is chiral-spin and $SU(4)$ symmetric.