Transverse target single-spin asymmetry in inclusive electroproduction of charged pions and kaons

TL;DR

This paper reports on measurements of single-spin asymmetries in the inclusive electroproduction of charged pions and kaons from transversely polarized protons, revealing positive asymmetries for positive hadrons and complex dependencies on kinematic variables.

Contribution

It provides the first detailed analysis of azimuthal asymmetries in charged pion and kaon production from transversely polarized protons at HERMES, highlighting specific kinematic dependencies.

Findings

Positive $ ext{sin}(\psi)$ asymmetries for positive pions and kaons.

Asymmetries vary with transverse momentum and are weakly dependent on $x_F$.

Large asymmetries observed in events with detected scattered electrons.

Abstract

Single-spin asymmetries were investigated in inclusive electroproduction of charged pions and kaons from transversely polarized protons at the HERMES experiment. The asymmetries were studied as a function of the azimuthal angle $\psi$ about the beam direction between the target-spin direction and the hadron production plane, the transverse hadron momentum relative to the direction of the incident beam, and the Feynman variable $x_F$. The $\sin(\psi)$ amplitudes are positive for positive pions and kaons, slightly negative for negative pions and consistent with zero for negative kaons, with particular transverse-momentum but weak $x_F$ dependences. Especially large asymmetries are observed for two small subsamples of events, where also the scattered electron was recorded by the spectrometer.