Topology in the SU(N_f) chiral symmetry restored phase of unquenched QCD and axion cosmology II

Abstract

We investigate the physical consequences of the survival of the effects of the U(1)_A anomaly in the chiral symmetric phase of QCD, and show that the free energy density is a singular function of the quark mass m, in the chiral limit, and that the $\sigma$ and $\bar{\pi }$ susceptibilities diverge in this limit at any $T\ge T_c$. We also show that the difference between the $\bar{\pi }$ and $\bar{\delta }$ susceptibilities diverges in the chiral limit at any $T\ge T_c$, a result which seems to be excluded by recent results of Tomiya et al. from numerical simulations of two-flavor QCD. We also discuss on the generalization of these results to the $N_f\ge 3$ model.

9 pages, no figures, new references added

References in corpus (5)

• Microscopic Origin of \boldmath{$U_A(1)$} Symmetry Violation in the High Temperature Phase of QCD
• Lattice QCD for Cosmology
• On the strength of the $U_A(1)$ anomaly at the chiral phase transition in $N_f=2$ QCD
• Topology in the SU(Nf) chiral symmetry restored phase of unquenched QCD and axion cosmology
• Lattice QCD at nonzero temperature and density

Cited by in corpus (5)

• Axions, Instantons, and the Lattice
• Massive Schwinger model at finite $\theta$
• Axial U(1) symmetry, topology, and Dirac spectra at high temperature in $N_f=2$ lattice QCD
• Interplay between $SU(N_f)$ chiral symmetry, $U(1{)}_A$ axial anomaly and massless bosons
• Spectral density of the Dirac-Ginsparg-Wilson operator, chiral $U(1{)}_A$ anomaly, and analyticity in the high temperature phase of $QCD$