The $g_T(x)$ contribution to single spin asymmetries in SIDIS

Abstract

Motivated by a novel origin of transverse single spin asymmetry (SSA) in semi-inclusive Deep Inelastic Scattering (SIDIS) uncovered by some of us, we quantitatively investigate its impact on the theoretical understanding of the mechanism responsible for SSA. This new contribution from the quark-initiated channel first appears in two-loop perturbation theory and involves the $g_T(x)$ distribution. We point out another entirely analogous piece from the gluon-initiated channel proportional to the gluon helicity distribution $\Delta G(x)$. Both contributions are solely expressed in terms of twist-two polarized parton distribution functions and twist-two fragmentation functions in the Wandzura-Wilczek approximation, such that they can be unambiguously evaluated without introducing free parameters. We make predictions for measurements of the asymmetries $A_{UT}$ at the future Electron-Ion Collider (EIC), and find that $A_{UT}$ associated with the $\sin ({\varphi }_h-{\varphi }_S)$, $\sin {\varphi }_S$ and $\sin (2{\varphi }_h-{\varphi }_S)$ harmonics can reach up to 1-2\% even at the top EIC energy.

28 pages, 8 figures

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Cited by in corpus (8)

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• Transverse Polarization of Hyperons Produced in Semi-Inclusive Deep Inelastic Scattering
• Perturbative $T$-odd asymmetries in the Drell-Yan process revisited
• On the odderon mechanism for transverse single spin asymmetry in the Wandzura-Wilczek approximation
• Gluonic contributions to semi-inclusive DIS in the target fragmentation region
• T-odd proton-helicity asymmetry in semi-inclusive DIS in perturbative QCD
• Single spin asymmetry in forward $pA$ collisions from Pomeron-Odderon interference