Multidimensional, high precision measurements of beam single spin asymmetries in semi-inclusive $\pi^{+}$ electroproduction off protons in the valence region

TL;DR

This paper presents high precision, multidimensional measurements of beam single spin asymmetries in semi-inclusive $^{+}$ electroproduction from protons, providing insights into nucleon structure and quark-gluon dynamics.

Contribution

It offers the first high precision multidimensional dataset of beam spin asymmetries in semi-inclusive pion production over a broad kinematic range, advancing understanding of twist-3 effects and nucleon structure.

Findings

Determined the structure function ratio $F^{\\sin\\phi}_{LU}/F_{UU}$ across kinematics.

Observed kinematic dependence of twist-3 contributions.

Provided data to test theoretical models of parton distributions.

Abstract

High precision measurements of the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering (SIDIS) from the proton have been performed using a 10.6~GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. We report here a high precision multidimensional study of single $\pi^{+}$ SIDIS data over a large kinematic range in Bjorken x, fractional energy and transverse momentum of the hadron as well as photon virtualities $Q^{2}$ ranging from $1-7\,$GeV$^{2}$. In particular, the structure function ratio $F^{\sin\phi}_{LU}/F_{UU}$ has been determined, where $F^{\sin\phi}_{LU}$ is a twist-3 quantity that can reveal novel aspects of emergent hadron mass and quark-gluon correlations within the nucleon. The data's impact on the evolving understanding of the underlying reaction mechanisms and their kinematic variation is explored using theoretical models for the different contributing transverse momentum dependent parton distribution functions.