Mass-suppressed effects in heavy quark diffusion

TL;DR

This paper investigates subleading mass-suppressed effects in heavy quark diffusion, highlighting the importance of non-perturbative contributions and the relevance of magnetic correlators for more accurate charm quark modeling.

Contribution

It extends the analysis of heavy quark diffusion by including $O(1/M^2)$ corrections and identifies the significance of non-perturbative effects in the transport coefficients.

Findings

Leading corrections are suppressed by $O(T/M)$

Magnetic correlators can extract relevant transport coefficients

Non-perturbative effects are crucial at leading order

Abstract

Many lattice studies of heavy quark diffusion originate from a colour-electric correlator, obtained as a leading term after an expansion in the inverse of the heavy-quark mass. In view of the fact that the charm quark is not particularly heavy, we consider subleading terms in the expansion. Working out correlators up to $O(1/M^2)$, we argue that the leading corrections are suppressed by $O(T/M)$, and one of them can be extracted from a colour-magnetic correlator. The corresponding transport coefficient is non-perturbative already at leading order in the weak-coupling expansion, and therefore requires a non-perturbative determination.