Heavy quarkonium correlators at finite temperature: QCD sum rule approach

TL;DR

This paper uses QCD sum rules to analyze how heavy quarkonium properties like mass and width change at finite temperature, revealing abrupt modifications near the phase transition and comparing results with lattice QCD data.

Contribution

It introduces a temperature-dependent continuum threshold in QCD sum rules and connects spectral modifications to lattice QCD correlator ratios.

Findings

At least one quarkonium property changes abruptly near the phase transition

The ratio G/G_rec remains nearly constant due to spectral modifications

The model spectral function aligns with lattice QCD results

Abstract

We investigate the properties of heavy quarkonia at finite temperature in detail using QCD sum rules. Extending previous analyses, we take into account a temperature dependent effective continuum threshold and derive constraints on the mass, the width, and the varying effective continuum threshold. We find that at least one of these quantities of a charmonium changes abruptly in the vicinity of the phase transition. We also calculate the ratio of the imaginary time correlator to its reconstructed one, $G/G_{\text{rec}}$, by constructing a model spectral function and compare it to the corresponding lattice QCD results. We demonstrate that the almost constant unity of $G/G_{\text{rec}}$ can be obtained from the destructive interplay of the changes in each part of the spectral modification which are extracted from QCD sum rules.