Transverse single spin asymmetry in Drell-Yan production in polarized pA collisions

TL;DR

This paper investigates the transverse single spin asymmetry in Drell-Yan production during polarized proton-nucleus collisions, using a hybrid approach that accounts for color entanglement effects at high transverse momentum.

Contribution

It introduces a hybrid calculation method for spin asymmetry in Drell-Yan processes that incorporates color entanglement effects at high transverse momentum.

Findings

Hybrid approach aligns with TMD factorization at low transverse momentum.

Color entanglement influences spin asymmetry at high transverse momentum.

Color entanglement effect is suppressed by 1/Nc^2.

Abstract

We study the transverse single spin asymmetry in Drell-Yan production in pA collisions with incoming protons being transversely polarized. We carry out the calculation using a newly developed hybrid approach. The polarized cross section computed in the hybrid approach is consistent with that obtained from the usual TMD factorization at low transverse momentum as expected, whereas at high transverse momentum, color entanglement effect is found to play a role in contributing to the spin asymmetry of Drell-Yan production, though it is a $1/N_c^2$ suppressed effect.