Nuclear dependence of azimuthal asymmetry in semi-inclusive deep inelastic scattering

TL;DR

This paper investigates how nuclear effects, specifically multiple scattering, suppress the azimuthal asymmetry in semi-inclusive deep inelastic scattering, revealing dependence on the shape of transverse momentum distributions.

Contribution

It introduces a framework to analyze nuclear dependence of azimuthal asymmetry in SIDIS, incorporating twist-2 and 3 TMD quark distributions and their broadening effects.

Findings

Azimuthal asymmetry is suppressed by multiple scattering.

Suppression depends on the shape of TMD distributions.

Gaussian model demonstrates nuclear dependence and smearing effects.

Abstract

Within the framework of a generalized factorization, semi-inclusive deeply inelastic scattering (SIDIS) cross sections can be expressed as a series of products of collinear hard parts and transverse-momentum-dependent (TMD) parton distributions and correlations. The azimuthal asymmetry <cos\phi>$ of unpolarized SIDIS in the small transverse momentum region will depend on both twist-2 and 3 TMD quark distributions in target nucleons or nuclei. Nuclear broadening of these twist-2 and 3 quark distributions due to final-state multiple scattering in nuclei is investigated and the nuclear dependence of the azimuthal asymmetry $<\cos\phi>$ is studied. It is shown that the azimuthal asymmetry is suppressed by multiple parton scattering and the transverse momentum dependence of the suppression depends on the relative shape of the twist-2 and 3 quark distributions in the nucleon. A Gaussian ansatz for TMD twist-2 and 3 quark distributions in nucleon is used to demonstrate the nuclear dependence of the azimuthal asymmetry and to estimate the smearing effect due to fragmentation.