Screening of light mesons and charmonia at high temperature

TL;DR

This study uses lattice QCD to analyze the behavior of light mesons and charmonia screening masses at high temperatures, revealing persistent mass splittings and partial symmetry restoration.

Contribution

It provides new lattice QCD results on meson screening masses at finite temperature with realistic quark masses, highlighting non-restoration of axial symmetry and charmonium mass stability.

Findings

Pseudo-scalar and scalar light meson screening masses do not degenerate at the chiral crossover.

Splitting between vector and pseudo-scalar screening masses persists at high temperature.

Charmonium screening masses remain close to zero-temperature masses below 300 MeV.

Abstract

We present lattice QCD results for the screening masses of light mesons and charmonia. The lattice computations were performed with 2+1 flavors of improved staggered quarks using quark masses which correspond to realistic pion and kaon masses at zero temperature. For the light quark sector we have found that the screening masses in the pseudo-scalar and the isovector scalar channels do not become degenerate at the chiral crossover temperature indicating an effective non-restoration of the axial symmetry. Also the splitting between the vector and the pseudo-scalar screening masses persists even in the limit of zero lattice spacing and at a moderately high temperature around 420 MeV. In the charmonium sector our investigation shows that the screening masses of the pseudo-scalar and the vector charmonia are almost (within a few percent) equal to their zero temperature masses for temperatures less than 300 MeV. We also present results for the charmonium screening masses using periodic boundary conditions along the temporal direction and discuss their implications.