Fragmentation contributions to transverse nucleon spin observables in semi-inclusive deep-inelastic scattering at NLO

TL;DR

This paper investigates the role of fragmentation contributions to transverse spin observables in semi-inclusive deep-inelastic scattering at NLO, confirming collinear twist-3 factorization and providing numerical predictions aligned with experimental data.

Contribution

It presents the first NLO analysis of fragmentation contributions to transverse spin asymmetries in SIDIS within collinear twist-3 factorization framework.

Findings

Collinear twist-3 factorization holds at one-loop level for these contributions.

NLO formulae are consistent with HERMES data.

Numerical predictions are provided for EIC kinematics.

Abstract

We study the spin-dependent cross section in semi-inclusive deep-inelastic lepton-nucleon collisions, $\ell + N^\uparrow\to \ell+h+X$. We focus on the cross section that is integrated over the transverse momentum $P_{h\perp}$ of the detected unpolarized hadron. We analyze this cross section at large virtuality $Q^2$ of the exchanged virtual photon within the framework of collinear twist-3 factorization in perturbative QCD. The two main transverse spin observables, the single nucleon spin asymmetry (SSA) and the double longitudinal lepton-transverse nucleon spin asymmetry (DSA), both receive contributions from chiral-odd twist-3 three-parton fragmentation functions. We study these fragmentation contributions to Next-To-Leading Order (NLO) in perturbative QCD. We explicitly observe that collinear twist-3 factorization holds for these contributions at the one-loop level. We confront our NLO formulae with HERMES data and provide numerical predictions for EIC kinematics.