Heavy Quarkonium Production in Single Transverse Polarized High Energy Scattering

TL;DR

This paper investigates the single transverse spin asymmetry in heavy quarkonium production during high-energy lepton-nucleon and nucleon-nucleon collisions, revealing its dependence on the production mechanism and color state configurations.

Contribution

It formulates the asymmetry in the non-relativistic limit and clarifies how final and initial state interactions influence the asymmetry in different collision types.

Findings

Asymmetry is sensitive to the production mechanism.

In ep collisions, asymmetry is nonzero only in the color-octet model.

In pp collisions, asymmetry is nonzero only in the color-singlet model.

Abstract

We formulate the single transverse spin asymmetry in heavy quarkonium production in lepton-nucleon and nucleon-nucleon collisions in the non-relativistic limit. We find that the asymmetry is very sensitive to the production mechanism. The final state interactions with the heavy quark and antiquark cancel out among themselves when the pair are produced in a color-single configuration, or cancel out with the initial state interaction in pp scattering when they are in color-octet. As a consequence, the asymmetry is nonzero in ep collisions only in the color-octet model, whereas in pp collisions only in the color-singlet model.