Extraction of Quark Transversity Distribution and Collins Fragmentation Functions with QCD Evolution

TL;DR

This paper performs a comprehensive analysis of the TMD evolution of Collins asymmetries in various processes, extracting transversity and Collins functions with NLL accuracy, and providing predictions for future experiments.

Contribution

It introduces a global analysis incorporating NLL TMD evolution to extract transversity and Collins functions from diverse experimental data.

Findings

Successful extraction of transversity distributions for u and d quarks.

Quantitative assessment of evolution effects and theoretical uncertainties.

Predictions for future experimental measurements.

Abstract

We study the transverse momentum dependent (TMD) evolution of the Collins azimuthal asymmetries in $e^+e^-$ annihilations and semi-inclusive hadron production in deep inelastic scattering (SIDIS) processes. All the relevant coefficients are calculated up to the next-to-leading logarithmic (NLL) order accuracy. By applying the TMD evolution at the approximate NLL order in the Collins-Soper-Sterman (CSS) formalism, we extract transversity distributions for $u$ and $d$ quarks and Collins fragmentation functions from current experimental data by a global analysis of the Collins asymmetries in back-to-back di-hadron productions in $e^+e^-$ annihilations measured by BELLE and BABAR Collaborations and SIDIS data from HERMES, COMPASS, and JLab HALL A experiments. The impact of the evolution effects and the relevant theoretical uncertainties are discussed. We further discuss the TMD interpretation for our results, and illustrate the unpolarized quark distribution, transversity distribution, unpolarized quark fragmentation and Collins fragmentation functions depending on the transverse momentum and the hard momentum scale. We make detailed predictions for future experiments and discuss their impact.