A lattice test of strong coupling behaviour in QCD at finite temperature

TL;DR

This paper proposes lattice measurements to test whether the quark-gluon plasma at high temperatures exhibits strong coupling characteristics, focusing on the behavior of twist-two operators and their anomalous dimensions.

Contribution

It introduces a novel set of lattice observables to distinguish strong versus weak coupling regimes in high-temperature QCD, especially through the analysis of twist-two operators.

Findings

Potential suppression of expectation values in strong coupling scenarios

Identification of the quark energy-momentum tensor behavior in quenched QCD

Method to test the pointlike nature of plasma constituents

Abstract

We propose a set of lattice measurements which could test whether the deconfined, quark-gluon plasma, phase of QCD shows strong coupling aspects at temperatures a few times the critical temperature for deconfinement, in the region where the conformal anomaly becomes unimportant. The measurements refer to twist-two operators which are not protected by symmetries and which in a strong-coupling scenario would develop large, negative, anomalous dimensions, resulting in a strong suppression of the respective lattice expectation values in the continuum limit. Special emphasis is put on the respective operator with lowest spin (the spin-2 operator orthogonal to the energy-momentum tensor within the renormalization flow) and on the case of quenched QCD, where this operator is known for arbitrary values of the coupling: this is the quark energy-momentum tensor. The proposed lattice measurements could also test whether the plasma constituents are pointlike (as expected at weak coupling), or not.