Double parton distributions in the nucleon from lattice simulations

TL;DR

This paper presents the first lattice QCD calculations of Mellin moments of double parton distributions in the nucleon, providing insights into quark correlations and flavor-polarization combinations.

Contribution

It introduces a novel lattice approach to compute Mellin moments of DPDs, considering various flavor and polarization combinations with clear signals for most Wick contractions.

Findings

Successful extraction of signals for multiple Wick contractions

First lattice-based estimates of DPD Mellin moments in the nucleon

Analysis of flavor and polarization dependence of DPDs

Abstract

We provide a first study of Mellin moments of double parton distributions (DPDs) in the nucleon on the lattice, where we consider several combinations of quark flavors and polarizations. These are accessible through two-current correlations, which can be obtained by evaluating four-point functions. In this context we consider all possible Wick contractions, where for almost all of them sufficiently clear signals are obtained. In the present 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 $m_K = 441\ \mathrm{MeV}$.