Speaker
Description
Screening masses of states with nucleon quantum numbers are determined, for the first time, in QCD for temperatures ranging from $\sim 1$ GeV up to $\sim 160$ GeV. The non-perturbative data show that the bulk of the screening mass is given by the tree level value $3\pi T$, while interactions induce a $4 -8 \%$ positive deviation for all temperatures considered. While our results are compatible with the $\mathcal{O}(g^2)$ perturbative prediction at very high temperatures, higher powers of the QCD coupling $g$ are required to explain the data's behaviour over the whole temperature range. Restoration of chiral symmetry is manifest in the degeneracy of the positive and negative parity state's screening mass, which differ by hundreds of MeV at zero temperature.
The non-perturbative data is obtained from Lattice QCD, employing a recently proposed strategy to reach very high temperatures. We complement this study with a NLO computation of the screening mass in the 3d effective theory describing QCD at high temperatures to obtain the $\mathcal{O}(g^2)$ perturbative result.
