engleski

gT(x) contribution to single spin asymmetries in SIDIS

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 ΔG(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 AUT at the future electron-ion collider (EIC), and find that AUT associated with the sin(ϕ_h − ϕ_S), sinϕ_S and sin(2ϕ_h − ϕ_S) harmonics can reach up to 1–2% even at the top EIC energy.

Single spin asymmetries ; SIDIS

nije evidentirano