Measurement of Beam-Spin Asymmetries for Deep Inelastic $\pi^+$ Electroproduction

TL;DR

This paper presents the first evidence of a non-zero beam-spin azimuthal asymmetry in deep-inelastic electroproduction of positive pions, revealing insights into nucleon structure through polarized electron scattering.

Contribution

It provides the first measurement of beam-spin asymmetries in $ ext{π}^+$ electroproduction in the deep-inelastic region using CLAS at JLab.

Findings

Non-zero $ ext{sin}\phi$ asymmetry observed.

Asymmetry amplitude increases with pion momentum fraction $z$.

Average asymmetry amplitude is approximately 0.038.

Abstract

We report the first evidence for a non-zero beam-spin azimuthal asymmetry in the electroproduction of positive pions in the deep-inelastic region. Data have been obtained using a polarized electron beam of 4.3 GeV with the CLAS detector at the Thomas Jefferson National Accelerator Facility (JLab). The amplitude of the $\sin\phi$ modulation increases with the momentum of the pion relative to the virtual photon, $z$, with an average amplitude of $0.038 \pm 0.005 \pm 0.003$ for $0.5 < z < 0.8$ range.