Three-loop non-singlet matching coefficients for heavy quark currents

TL;DR

This paper calculates three-loop non-singlet matching coefficients for heavy quark currents in QCD and NRQCD, significantly improving numerical precision and confirming previous results for the vector current.

Contribution

It provides the first three-loop calculations of these matching coefficients with high numerical accuracy, enhancing precision over prior work.

Findings

Confirmed previous vector current results with higher accuracy

Provided new three-loop non-singlet matching coefficients

Achieved numerical precision of about ten digits

Abstract

We compute the matching coefficients between QCD and non-relativistic QCD for external vector, axial-vector, scalar and pseudo-scalar currents up to three-loop order. We concentrate on the non-singlet contributions and present precise numerical results with an accuracy of about ten digits. For the vector current the results from arXiv:1401.3004 are confirmed, increasing the accuracy by several orders of magnitude.