Probing transverse quark polarization via azimuthal asymmetries in leptoproduction
A. M. Kotzinian, P. J. Mulders
TL;DR
This work addresses how to access transverse quark polarization through azimuthal asymmetries in leptoproduction at leading order by exploiting transverse-momentum dependent quark distributions and fragmentation functions. It derives the polarized SIDIS cross section in terms of TMDs and Collins functions, and introduces weighted observables $I_1$–$I_4$ that project specific spin and angular dependencies, enabling extraction of $g_{1T}^{(1)}$, $h_{1L}^{\perp(1)}$, and $H_1^{\perp(1)}$. The authors then implement Wandzura–Wilczek-type approximations to relate poorly known TMDs to collinear PDFs and propose Collins-based parametric forms to estimate $H_1^{\perp(1)}$, providing a practical framework for phenomenology with inputs from existing PDF parameterizations. The findings offer a path to probe the transverse spin structure of the nucleon in SIDIS and quantify the Collins effect through weighted cross sections, with implications for interpreting azimuthal asymmetries in polarized scattering experiments.
Abstract
We consider the leading order result for polarized leptoproduction, putting emphasis on transverse momentum dependent effects appearing in azimuthal asymmetries. Measurements of weighted cross sections enable extraction of the distribution of transversely polarized quarks. We focus on the distribution in a longitudinally polarized hadron and estimate the expected asymmetries in leptoproduction.