Charm and beauty in the deconfined plasma from quenched lattice QCD

TL;DR

This study uses quenched lattice QCD to analyze charmonium and bottomonium correlators across temperatures, comparing results with perturbative theories and estimating quark diffusion coefficients, revealing different resonance behaviors for charm and bottom quarks.

Contribution

It provides continuum-extrapolated lattice results for quarkonium correlators, compares them with perturbative models, and estimates quark diffusion coefficients in the deconfined plasma.

Findings

Charmonium correlators match perturbative results above T_c without resonance peaks at 1.1 T_c.

Bottomonium correlators require a resonance peak up to 1.5 T_c.

Charm quark diffusion coefficient exceeds that of the bottom quark.

Abstract

We present continuum extrapolated results of charmonium and bottomonium correlators in the vector channel at several temperatures below and above $T_c$. The continuum extrapolation jointly performed with the interpolations to have physical values of $J/\psi$ and $\Upsilon$ masses in the confined phase is based on calculations on several large quenched isotropic lattices using clover-improved Wilson valence fermions carrying different quark masses. The extrapolated lattice correlators are confronted with perturbation theory results incorporating resummed thermal effects around the threshold from pNRQCD and vacuum asymptotics above the threshold. An additional transport peak is modelled below the threshold allowing for an estimate of the diffusion coefficients for charm and bottom quarks. We find that charmonium correlators in the vector channel can be well reproduced by perturbative spectral functions above $T_c$ where no resonance peaks for $J/\psi$ are needed at and above 1.1 $T_c$, while for bottomonium correlators a resonance peak for $\Upsilon$ is still needed up to 1.5 $T_c$. By analyzing the transport contribution to the correlators we find that the drag coefficient of a charm quark is larger than that of a bottom quark.