Role of axial-vector mesons near the chiral phase transition

TL;DR

This paper investigates how axial-vector mesons and their mixing with vector mesons evolve near the chiral phase transition, revealing mass degeneracy and vanishing mixing at the critical temperature.

Contribution

It provides a systematic analysis of vector--axial-vector mixing and meson mass behavior near the chiral phase transition using an effective field theory approach.

Findings

V-A mixing vanishes at the critical temperature.

$ ho$ and $a_1$ meson masses become nearly degenerate at $T_c$.

V-A mixing remains approximately zero at $T_c$.

Abstract

We present a systematic study of the vector--axial-vector mixing (V-A mixing) in the current correlation functions and its evolution with temperature within an effective field theory. The $a_1$-$\rho$-$\pi$ coupling vanishes at the critical temperature $T_c$ and thus the V-A mixing also vanishes. A remarkable observation is that even for finite $m_\pi$ the $\rho$ and $a_1$ meson masses are almost degenerate at $T_c$. The vanishing V-A mixing at $T_c$ stays approximately intact.