T-odd proton-helicity asymmetry in semi-inclusive DIS in perturbative QCD

TL;DR

This paper calculates the T-odd proton-helicity asymmetry in semi-inclusive deep-inelastic scattering using perturbative QCD, providing theoretical predictions relevant for current and future experiments.

Contribution

It introduces a lowest-order perturbative QCD calculation of the T-odd asymmetry in semi-inclusive DIS, linking collinear and transverse-momentum dependent formalisms.

Findings

Asymmetry is T-odd and arises from interference of tree and one-loop amplitudes.

Results are relevant for COMPASS, HERMES, and Electron-Ion Collider experiments.

Provides phenomenological estimates for spin asymmetries at large transverse momentum.

Abstract

We compute the single-spin asymmetry $A_{UL}$ in semi-inclusive deep-inelastic scattering of unpolarized leptons and longitudinally polarized protons at large transverse momentum of the produced hadron. Our calculation is performed in collinear factorization at the lowest order of QCD perturbation theory. For photon exchange the asymmetry is T-odd and receives contributions from the interference of the tree level and one-loop absorptive amplitudes. We consider the behavior of the spin asymmetry at low transverse momentum where contact to the formalism based on transverse-momentum dependent distribution functions can be made. We also present some phenomenological results relevant for the COMPASS and HERMES experiments and the future Electron-Ion Collider.