Quarkonium in a non-ideal hot QCD Plasma

TL;DR

This paper investigates how anisotropies in a hot QCD plasma affect quarkonium states, revealing increased decay widths and potential observable suppression in heavy-ion collision experiments.

Contribution

It provides a detailed analysis of the real-time propagator modifications due to anisotropies and their impact on quarkonium binding and decay in a non-ideal plasma.

Findings

Anisotropies lead to a larger imaginary part in the gluon propagator.

Quarkonium states have increased decay widths in anisotropic plasmas.

Potential suppression of Upsilon(1S) decay observed in heavy-ion collisions.

Abstract

Substantial anisotropies should occur in the hot expanding QCD plasma produced in relativistic heavy-ion collisions due to non-vanishing shear viscosity. We discuss the form of the real-time, hard thermal loop resummed propagator for static gluons in the presence of such anisotropies and the consequences for quarkonium binding. It has been predicted that the propagator develops an imaginary part due to Landau damping at high temperature. This generates a much larger width of quarkonium states than the Appelquist-Politzer vacuum estimate corresponding to decay into three gluons. We argue that this might be observable in heavy-ion collisions as a suppression of the Upsilon(1S) --> e+ e- process. Lastly, we consider the heavy quark (singlet) free energy just above the deconfinement temperature. In the "semi-QGP", F(R) at distances beyond 1/T is expected to be suppressed by 1/N as compared to an ideal plasma.