Aspects of chiral symmetry in QCD at T=128 MeV

We investigate several aspects of chiral symmetry in QCD at a temperature of T=128 MeV. The study is based on a 24×963 lattice-QCD ensemble with O(a)-improved Wilson quarks and physical up, down and strange quark masses. The pion quasiparticle turns out to be significantly lighter than the zero-temperature pion mass, even though the corresponding static correlation length is shorter. We perform a quantitative comparison of our findings to predictions of chiral perturbation theory. Among several order parameters for chiral symmetry restoration, we compute the difference of the vector- and axial-vector time-dependent correlators and find it to be reduced by a factor ∼2/3 as compared to its vacuum counterpart.