Intrinsic quark transverse momentum in the nucleon from lattice QCD

TL;DR

This paper uses lattice QCD to study the intrinsic transverse momentum distributions of quarks in the nucleon, revealing factorization properties and spin-dependent deformations relevant for understanding angular asymmetries.

Contribution

It introduces process-independent, gauge-invariant quark transverse momentum distributions and analyzes their properties in lattice QCD, highlighting factorization and spin-related deformations.

Findings

Longitudinal and transverse momentum dependence approximately factorizes.

Quark k_T-probability densities exhibit dipole deformations due to spin correlations.

Lattice calculations are based on N_f=2+1 mixed action propagators.

Abstract

A better understanding of transverse momentum (k_T-) dependent quark distributions in a hadron is needed to interpret several experimentally observed large angular asymmetries and to clarify the fundamental role of gauge links in non-abelian gauge theories. Based on manifestly non-local gauge invariant quark operators we introduce process-independent k_T-distributions and study their properties in lattice QCD. We find that the longitudinal and transverse momentum dependence approximately factorizes, in contrast to the behavior of generalized parton distributions. The resulting quark k_T-probability densities for the nucleon show characteristic dipole deformations due to correlations between intrinsic k_T and the quark or nucleon spin. Our lattice calculations are based on N_f=2+1 mixed action propagators of the LHP collaboration.