Two-current correlations and DPDs for the nucleon on the lattice

TL;DR

This study computes two-current correlation functions in the nucleon on the lattice, relating them to parton distributions and analyzing their spin and flavor dependencies, advancing understanding of nucleon structure.

Contribution

It provides the first lattice QCD calculation of four-point functions related to double parton distributions, including all Wick contractions and operator insertions.

Findings

Correlation functions related to parton distributions are computed.

Quark spin and flavor dependencies of double parton distributions are analyzed.

Results are obtained on a $96 imes 32^3$ lattice with physical parameters.

Abstract

We calculate correlation functions of two local operators within the nucleon carrying momentum. We resolve their dependence on the spatial distance of the currents. This is carried out for all Wick contractions, taking into account several operator insertion types. The resulting four-point functions can be related to parton distribution functions as well as to Mellin moments of double parton distributions. For the latter, we analyze their quark spin and flavor dependency. In this first study, we employ an $N_F = 2 + 1$ CLS ensemble on a $96 \times 32^3$ lattice with lattice spacing $a = 0.0856\ \mathrm{fm}$ and the pseudoscalar masses $m_\pi = 355\ \mathrm{MeV}$ and $m_K = 441\ \mathrm{MeV}$.