Twist-3 quark-gluon correlation contribution to single-transverse spin asymmetry for direct-photon and single-jet productions in pp collision

TL;DR

This paper investigates how twist-3 quark-gluon correlations influence single-transverse spin asymmetries in direct-photon and jet production during proton-proton collisions, revealing significant asymmetries in forward regions and negligible effects in backward regions.

Contribution

It provides the first detailed analysis of twist-3 quark-gluon contributions to these asymmetries at RHIC energies, highlighting the dominance of soft-gluon poles and their potential for probing nucleon structure.

Findings

Significant asymmetries in the forward region of the polarized nucleon.

Negligible asymmetries in the backward region.

Soft-fermion pole contribution is very small.

Abstract

We study the contribution of the collinear twist-3 quark-gluon correlation to the single transverse-spin asymmetry in direct-photon and single-jet productions in pp collision. At typical RHIC kinematics we find sizable asymmetries in the forward region of the polarized nucleon while they are almost zero in the backward region. We also find the soft-fermion pole contribution is vanishingly small, suggesting the measurement of these asymmetries provides us with an unique opportunity to determine the net soft-gluon pole function.