T-Matrix Approach to Quarkonium Correlation Functions in the QGP

TL;DR

This paper develops a T-matrix approach to study quarkonium states in the Quark Gluon Plasma, analyzing their dissolution with temperature and comparing spectral functions to lattice QCD results.

Contribution

It introduces a T-matrix framework based on lattice QCD inputs to unify the treatment of bound and scattering quarkonium states in the QGP.

Findings

Bound states dissolve above the Q-ar{Q} threshold at high temperature.

Spectral functions show large sensitivity to bound and scattering state interplay.

Finite-width effects significantly impact quark propagator behavior in the QGP.

Abstract

We study the evolution of heavy quarkonium states with temperature in a Quark Gluon Plasma (QGP) by evaluating the in-medium Q-\bar{Q} T-matrix within a reduced Bethe-Salpeter equation in both S- and P-wave channels. The underlying interaction kernel is extracted from recent finite-temperature QCD lattice calculations of the singlet free energy of a Q-\bar{Q} pair. The bound states are found to gradually move above the Q-\bar{Q} threshold after which they rapidly dissolve in the hot system. The T-matrix approach is particularly suited to investigate these mechanisms as it provides a unified treatment of bound and scattering states including threshold effects and the transition to the (perturbative) continuum. We apply the T-matrix to calculate Q-\bar{Q} spectral functions as well as pertinent Euclidean-time correlation functions which are compared to results from lattice QCD. A detailed analysis reveals large sensitivities to the interplay of bound and scattering states, to temperature dependent threshold energies and to the "reconstructed" correlator used for normalization. We furthermore investigate the impact of finite-width effects on the single-quark propagators in the QGP as estimated from recent applications of heavy-quark rescattering to RHIC data.