One-Loop Corrections of Single Spin Asymmetries in Semi-Inclusive DIS

TL;DR

This paper calculates one-loop corrections to single spin asymmetries in semi-inclusive deep inelastic scattering, providing theoretical predictions for measurable asymmetries that reveal hadron internal structure, relevant for current and future experiments.

Contribution

It presents the first one-loop level calculation of spin asymmetries in SIDIS, including the subtraction of collinear divergences, advancing the theoretical understanding of spin-dependent phenomena.

Findings

Predicted Sivers and Collins asymmetries at one-loop accuracy.

Calculated perturbative coefficient functions free of divergences.

Provided a framework for extracting nonperturbative functions from experiments.

Abstract

We study single spin asymmetries at one-loop accuracy in semi-inclusive DIS with a transversely polarized hadron in the initial state. Two measurable spin observables are predicted in the framework of QCD collinear factorization. One of the spin observables is the Sivers weighted asymmetry, another one is the Collins weighted asymmetry. The prediction takes a form of convolutions of perturbative coefficient functions and nonperturbative functions, which are twist-2 transversity distributions, twist-3 parton distributions, twist-2- and twist-3 parton fragmentation functions. These nonperturbative functions can be extracted from measurements of the spin observables and provide valuable information of the inner structure of hadrons. The measurements can be done in current COMPASS- and JLab experiments and in future experiments of EIC. The perturbative coefficient functions are calculated at one-loop level. There are collinear divergences in the calculation involving chirality-even- and chirality-odd twist operators. We find that all collinear divergences can be correctly subtracted so that the final results are finite.