The Compton amplitude and nucleon structure functions in lattice QCD

TL;DR

This paper discusses a lattice QCD approach to directly compute the Compton amplitude, enabling access to nucleon structure functions and overcoming challenges of traditional methods.

Contribution

It introduces a novel lattice QCD method using the Feynman-Hellmann theorem to calculate the Compton amplitude and nucleon structure function moments.

Findings

Progress in calculating the forward Compton amplitude.

Advances in investigating moments of nucleon structure functions.

Potential to bypass operator mixing and renormalization issues.

Abstract

The structure of hadrons relevant for deep-inelastic scattering are completely characterised by the Compton amplitude. A direct calculation of the Compton amplitude in a lattice QCD setup provides a way to accessing the structure functions, circumventing the operator mixing and renormalisation issues of the standard operator product expansion approach. In this contribution, we focus on the QCDSF/UKQCD Collaboration's advances in calculating the forward Compton amplitude via an implementation of the second-order Feynman-Hellmann theorem. We highlight our progress in investigating the moments of nucleon structure functions.