Renormalon-chain contributions to two-point correlators of nonlocal quark currents

TL;DR

This paper computes the perturbative contributions to two-point correlators of nonlocal quark currents in massless QCD, focusing on chain diagrams within the large $n_f$ approximation, relevant for meson distribution amplitudes.

Contribution

It provides a detailed calculation of renormalon-chain contributions to nonlocal quark current correlators in massless QCD, extending previous special-case results.

Findings

Results align with existing literature on special cases.

Functional analysis of correlators offers insights for phenomenology.

Perturbative contributions inform meson distribution amplitudes.

Abstract

We calculate, within massless QCD, a two-point correlator of nonlocal (composite) vector quark currents with arbitrary-length chains of the simplest fermion loops being inserted into gluon lines. Within the large $n_f$ (or large $\beta_0$) approximation, the correlator defines a perturbative contribution to the leading-twist distribution amplitudes for light mesons. Our results are consistent with a number of special cases in the literature. We consider functionals of the correlator, which are important for the phenomenology, and their properties as function series.