Speaker
Description
Previous Lattice QCD calculations of nucleon transverse momentum-dependent parton distributions (TMDs) focused on the case of transversely polarized nucleons, and thus did not encompass two leading-twist TMDs associated with longitudinal polarization, namely, the helicity TMD $g_1 $ and the worm-gear TMD $h_{1L}^{\perp } $ corresponding to transversely polarized quarks in a longitudinally polarized nucleon. Based on a definition of TMDs via hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections, TMD observables characterizing the aforementioned two TMDs are evaluated, utilizing a RBC/UKQCD domain wall fermion ensemble at the physical pion mass. The results suggest that $h_{1L}^{\perp } $ is significantly suppressed in magnitude compared to its counterpart, the worm-gear TMD $g_{1T} $, deviating from the generic prediction of quark models, and thus indicating the influence of strong gluonic dynamical effects.
