QCD determination of the axial-vector coupling of the nucleon at finite temperature

Abstract

A thermal QCD Finite Energy Sum Rule (FESR) is used to obtain the temperature dependence of the axial-vector coupling of the nucleon, $g_A(T)$. We find that $g_A(T)$ is essentially independent of $T$, in the very wide range $0\le T\le 0.9T_c$, where $T_c$ is the critical temperature. While $g_A$ at T=0 is $q^2$-independent, it develops a $q^2$ dependence at finite temperature. We then obtain the mean square radius associated with $g_A$ and find that it diverges at $T=T_c$, thus signalling quark deconfinement. As a byproduct, we study the temperature dependence of the Goldberger-Treiman relation.

Comments: 8 pages and 3 figures