How to compute the thermal quarkonium spectral function from first principles?

TL;DR

This paper discusses a systematic method to compute the thermal quarkonium spectral function from first principles using effective field theories in the weak-coupling regime at high temperature and large quark mass.

Contribution

It introduces a scale hierarchy framework and effective field theories to analyze the melting of quarkonium spectral peaks at high temperature.

Findings

Identifies the relevant scale hierarchy for quarkonium melting.

Provides a parametric description of the melting temperature.

Outlines a step-by-step effective field theory approach.

Abstract

In the limit of a high temperature T and a large quark-mass M, implying a small gauge coupling g, the heavy quark contribution to the spectral function of the electromagnetic current can be computed systematically in the weak-coupling expansion. We argue that the scale hierarchy relevant for addressing the disappearance ("melting") of the resonance peak from the spectral function reads M >> T > g^2 M > gT >> g^4 M, and review how the heavy scales can be integrated out one-by-one, to construct a set of effective field theories describing the low-energy dynamics. The parametric behaviour of the melting temperature in the weak-coupling limit is specified.