Speaker
Description
The classical U(1) axial symmetry of the QCD lagrangian is broken by the quantum anomaly, but may be effectively restored at high temperature. Whether or not this effective restoration coincides with the chiral transition has been the subject of much debate. Both chiral and axial symmetries can be investigated through degeneracies of mesonic correlators and their associated susceptibilities. We present results for vector--axial-vector and scalar--pseudoscalar degeneracies from anisotropic lattice ensembles generated by the FASTSUM collaboration. We find evidence that the $U(1)_A$ symmetry is effectively restored at $\sim300$ MeV, well above the chiral transition temperature.
We also present results for the static quark potential using several different methods (BR spectral reconstruction, UV subtracted gaussian and lorentzian fits, and the Bala-Datta method). We find clear evidence of screening in the real part of the potential at very high temperature, but no agreement between the different methods at intermediate temperatures.