# Matching coefficients in NRQCD to two-loop accuracy

## TL;DR

This paper computes two-loop matching coefficients in NRQCD up to order 1/m^2, providing essential components for high-precision calculations of top quark pair production and heavy quarkonium decay.

## Contribution

It presents the first two-loop calculations of key matching coefficients in NRQCD, advancing precision in theoretical predictions for heavy quark processes.

## Key findings

- Analytic results for matching coefficients in a general covariant gauge.
- Foundation for higher-order corrections in top quark and quarkonium physics.
- Techniques for two-loop calculations in effective field theories.

## Abstract

We consider the Lagrange density of non-relativistic Quantum Chromodynamics expanded up to order $1/m^2$, where $m$ is the heavy quark mass, and compute several matching coefficients up to two-loop order. Our results are building blocks for next-to-next-to-next-to-leading logarithmic and next-to-next-to-next-to-next-to-leading order corrections to the threshold production of top quark pairs and the decay of heavy quarkonia. We describe the techniques used for the calculation and provide analytic results for a general covariant gauge.