T-dependence of the axion mass when the U_A(1) and chiral symmetry breaking are tied

Abstract

Modulo the scale of spontaneous breaking of Peccei-Quinn symmetry, the axion mass $m_a(T)$ is given by the QCD topological susceptibility $\chi (T)$ at all temperatures $T$. From an approach tying the $U_A(1)$ and chiral symmetry breaking and getting good $T$-dependence of $\eta$ and $\eta$ mesons, we get $\chi (T)$ for an effective Dyson-Schwinger model of nonperturbative QCD. Comparison with lattice results for $\chi (T)$, and thus also for $m_a(T)$, shows good agreement for temperatures ranging from zero up to the double of the chiral restoration temperature $T_c$.

Comments: appolb.cls, 6 pages, 1 figure, condensed version of the part of arXiv:1909.09879 presented at Excited QCD 2019, to appear in Acta Physica Polonica B Proceedings Supplement