Azimuthal distributions of charged hadrons, pions, and kaons produced in deep-inelastic scattering off unpolarized protons and deuterons

TL;DR

This paper reports the first measurement of azimuthal modulations in semi-inclusive deep-inelastic scattering, revealing insights into quark transverse motion and polarization within nucleons through detailed four-dimensional kinematic analysis.

Contribution

It introduces the first four-dimensional measurement of azimuthal modulations for various hadrons in unpolarized SIDIS, enhancing understanding of quark transverse dynamics.

Findings

Measured cosφ and cos2φ modulations for pions and kaons

Separated positive and negative hadron contributions

Provided data sensitive to quark transverse motion and polarization

Abstract

The azimuthal cos{\phi} and cos2{\phi} modulations of the distribution of hadrons produced in unpolarized semi-inclusive deep-inelastic scattering of electrons and positrons off hydrogen and deuterium targets have been measured in the HERMES experiment. For the first time these modulations were determined in a four-dimensional kinematic space for positively and negatively charged pions and kaons separately, as well as for unidentified hadrons. These azimuthal dependences are sensitive to the transverse motion and polarization of the quarks within the nucleon via, e.g., the Cahn, Boer-Mulders and Collins effects.