First global QCD analysis of the TMD ${\mathbf{g}}_{1\mathbf{T}}$ from semi-inclusive DIS data

Abstract

The worm-gear transverse momentum dependent (TMD) function $g_{1T}$ is one of the eight leading-twist TMDs and has the probabilistic interpretation of finding a longitudinally polarized quark inside a transversely polarized hadron. In this work, we present the first simultaneous extraction of $g_{1T}$ from all the available experimental measurements. The study involves the analysis of COMPASS, HERMES, and Jefferson Lab data on semi-inclusive deep-inelastic scattering using Monte Carlo techniques. We also compare $g_{1T}$ obtained from this experimental data with different theoretical approaches, such as the large-$N_c$ approximation, the Wandzura-Wilczek-type approximation, and lattice QCD.

Comments: Version accepted for PRD: Minor additions to the text; Expanded Appendix (Appendix A) with an additional figure; Updated References; 19 pages, 18 figures