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.

http://arxiv.org/icons/sfx.gif