Left-right spin asymmetry in $\ell N^\uparrow \to h X$

TL;DR

This paper calculates the left-right spin asymmetry in lepton-nucleon scattering with a transversely polarized nucleon using twist-3 collinear factorization, comparing results with experimental data and providing future predictions.

Contribution

It presents a twist-3 collinear factorization calculation of the left-right asymmetry in lepton-nucleon scattering, incorporating non-perturbative correlators fixed from other processes.

Findings

Results agree in sign with experimental data.

Computed asymmetries are larger than observed.

Predictions for future Electron Ion Collider experiments.

Abstract

We consider the inclusive production of hadrons in lepton-nucleon scattering. For a transversely polarized nucleon this reaction shows a left-right azimuthal asymmetry, which we compute in twist-3 collinear factorization at leading order in perturbation theory. All non-perturbative parton correlators of the calculation are fixed through information from other hard processes. Our results for the left-right asymmetry agree in sign with recent data for charged pion production from the HERMES Collaboration and from Jefferson Lab. However, the magnitude of the computed asymmetries tends to be larger than the data. Potential reasons for this outcome are identified. We also give predictions for future experiments and highlight in particular the unique opportunities at an Electron Ion Collider.