Evolution of twist-3 multi-parton correlation functions relevant to single transverse-spin asymmetry

TL;DR

This paper develops and analyzes the evolution equations for twist-3 multi-parton correlation functions responsible for single transverse-spin asymmetry in QCD, showing their scale dependence and similarities to DGLAP kernels.

Contribution

It introduces two sets of twist-3 correlation functions, derives their evolution equations, and calculates the relevant kernels at order alpha_s, advancing understanding of spin asymmetries in QCD.

Findings

Evolution kernels are infrared safe.

Kernels resemble DGLAP evolution kernels.

Explicit demonstration of scale dependence.

Abstract

We constructed two sets of twist-3 correlation functions that are responsible for generating the novel single transverse-spin asymmetry in the QCD collinear factorization approach. We derive evolution equations for these universal three-parton correlation functions. We calculate evolution kernels relevant to the gluonic pole contributions to the asymmetry at the order of $\alpha_s$. We find that all evolution kernels are infrared safe as they should be and have a lot in common to the DGLAP evolution kernels of unpolarized parton distributions. By solving the evolution equations, we explicitly demonstrate the factorization scale dependence of these twist-3 correlation functions.