Collins Fragmentation and the Single Transverse Spin Asymmetry

TL;DR

This paper investigates the Collins mechanism's role in single transverse spin asymmetries, demonstrating the universality of the Collins function and its consistency across different theoretical frameworks in semi-inclusive deep inelastic scattering.

Contribution

It identifies the twist-three fragmentation function related to the Collins mechanism and shows the universality and consistency of the Collins function across collinear and transverse momentum dependent approaches.

Findings

The Collins function is universal across different factorization schemes.

The Collins mechanism contributes significantly to single transverse spin asymmetries.

Theoretical approaches are consistent in the intermediate transverse momentum region.

Abstract

We study the Collins mechanism for the single transverse spin asymmetry in the collinear factorization approach. The correspondent twist-three fragmentation function is identified. We show that the Collins function calculated in this approach is universal. We further examine its contribution to the single transverse spin asymmetry of semi-inclusive hadron production in deep inelastic scattering and demonstrate that the transverse momentum dependent and twist-three collinear approaches are consistent in the intermediate transverse momentum region where both apply.