Moments of nucleon distribution amplitudes from irreducible three-quark operators

TL;DR

This paper reports on a lattice QCD calculation of moments of nucleon distribution amplitudes using irreducible three-quark operators, addressing operator renormalization and mixing to enable quantitative predictions.

Contribution

It introduces a method to control operator mixing in lattice QCD for nucleon distribution amplitudes using irreducible three-quark operators.

Findings

Preliminary results for leading-twist nucleon distribution amplitudes.

Implementation of irreducible three-quark operators for operator mixing control.

Use of 2-flavor dynamical clover fermion simulations.

Abstract

Semi-exclusive and exclusive processes are becoming more and more important in high energy physics since they are excellently suited to study the internal hadronic structure. To analyze such processes the knowledge of the hadron distribution amplitudes, which are universal for different reactions, is essential. Only rather indirect information on these nonperturbative functions can be obtained from measurements. In this work we report on a lattice QCD computation of moments of nucleon distribution amplitudes using suitable three-quark operators. However, these operators have to be renormalized and the mixing is even more complicated than in the continuum. Using the symmetry group of the hypercubic lattice we therefore derive and implement irreducibly transforming three-quark operators, which allow us to control the mixing pattern and will finally lead to quantitative predictions in the MSbar scheme. We present preliminary results for leading-twist and next-to-leading twist nucleon distribution amplitudes based on the QCDSF/UKQCD simulations with 2 flavors of dynamical clover fermions.