Nonperturbative Flavor Breaking in Topological Susceptibility at Hot QCD Criticality. (arXiv:2003.11375v1 [hep-ph])

<a href="http://arxiv.org/find/hep-ph/1/au:+Kawaguchi_M/0/1/0/all/0/1">Mamiya Kawaguchi</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Matsuzaki_S/0/1/0/all/0/1">Shinya Matsuzaki</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Tomiya_A/0/1/0/all/0/1">Akio Tomiya</a>

We show that the QCD topological susceptibility nonperturbatively gets a

significant contribution signaled by flavor-nonuniversal quark condensates at

around the pseudo-critical temperature of the chiral crossover. It implies a

remarkable flavor breaking in the axial anomaly as well as the QCD theta vacuum

in high temperature QCD, which are (almost) flavor universal in the vacuum. The

flavor breaking is triggered by nonperturbative thermal loop corrections, which

cannot be dictated by the low-energy expansion associated with the chiral

symmetry breaking, such as the chiral perturbation theory. This would give an

impact on the thermal history and the cosmological evolution of QCD axion

including the estimate of the relic abundance as a cold dark matter candidate.

Applications to heavy-ion collision-phenomenology would also be possible.

We show that the QCD topological susceptibility nonperturbatively gets a

significant contribution signaled by flavor-nonuniversal quark condensates at

around the pseudo-critical temperature of the chiral crossover. It implies a

remarkable flavor breaking in the axial anomaly as well as the QCD theta vacuum

in high temperature QCD, which are (almost) flavor universal in the vacuum. The

flavor breaking is triggered by nonperturbative thermal loop corrections, which

cannot be dictated by the low-energy expansion associated with the chiral

symmetry breaking, such as the chiral perturbation theory. This would give an

impact on the thermal history and the cosmological evolution of QCD axion

including the estimate of the relic abundance as a cold dark matter candidate.

Applications to heavy-ion collision-phenomenology would also be possible.

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