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

Understand

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.