Meson screening masses in ( 2+1 )-flavor QCD

Abstract

We present lattice QCD results for mesonic screening masses in the temperature range 140 MeV T 2500 MeV. Our calculations were carried out using (2+1)-flavors of the Highly Improved Staggered Quark (HISQ) action, with a physical value for the strange quark mass and two values of the light quark mass corresponding to pion masses of 160 MeV and 140 MeV. Continuumextrapolated results were obtained using calculations with a variety of lattice spacings corresponding to temporal lattice extents Nτ = 6 -16. We discuss the implications of these results for the effective restoration of various symmetries in the high temperature phase of QCD, as well as the approach toward the perturbative limit.

Interplay between SU(Nf) chiral symmetry, U(1)AAzcoiti1 2019Phys. Rev. D60122View full textAdd to dashboardCite

“…However, the results of Ref. [40] show a small change of the pion screening mass when crossing the critical temperature and a decreasing screening mass, at T ⪆ T c , when going from theūs to thē ud channel, compatible with a vanishing pion screening mass in the chiral limit.…”

“…There are, on the other hand, two recent lattice calculations of mesonic screening masses in two- [39] and threeflavor [40] QCD around and above the critical temperature. The reported results are not enough to allow a good check of our spectrum prediction.…”

Lattice QCD constraints on the heavy quark diffusion coefficient

“…This suggests that κ=T 3 should decrease from large values at temperatures close to the transition temperature to smaller values when the temperature is increasing. It would be interesting to see if contacts between the lattice and the perturbative calculations can be made for the heavy quark diffusion coefficient, as has already been done for the equation of state [29], quark number susceptibilities [30,31], and static correlation functions [32][33][34]. If such contacts can be established, these would validate the methodology used in the lattice extraction of κ.…”

Transverse momentum broadening from the lattice

“…There are a few techniques one can apply to improve that, however. Firstly, one can estimate starting values close to the final fit values, for which a procedure was outlined in [37]. The second method we apply is the so-called variable projection [38].…”