Transverse momentum distributions of quarks in the nucleon from Lattice QCD

TL;DR

This paper presents the first lattice QCD calculations of transverse momentum dependent parton distribution functions (TMDPDFs) in the nucleon, providing insights into quark motion and testing factorization assumptions.

Contribution

It introduces novel lattice QCD computations of polarized and unpolarized TMDPDFs, including the renormalization of non-local operators with Wilson lines.

Findings

First lattice results for TMDPDFs

Test of x and transverse momentum factorization

Renormalization of non-local operators with Wilson lines

Abstract

Transverse momentum dependent parton distribution functions (TMDPDFs) encode information about the intrinsic motion of quarks inside the nucleon. They are important non-perturbative ingredients in our understanding of, e.g., azimuthal asymmetries and other qualitative features in semi-inclusive deep inelastic scattering experiments. We present first calculations on the lattice, based on MILC gauge configurations and propagators from LHPC. They yield polarized and unpolarized transverse momentum dependent quark densities and enable us to test the assumption of factorization in x and transverse momentum. The operators we employ are non-local and contain a Wilson line, whose renormalization requires the removal of a divergence linear in the cutoff 1/a.