"Lattice QCD investigations of quark transverse momentum in hadrons"

Presented by Michael Engelhardt, New Mexico State University

Friday, February 19, 2016, 2:00 pm — Small Seminar Room, Bldg. 510

An ongoing program of evaluating transverse momentum
dependent parton distributions (TMDs) within lattice QCD
is reviewed, summarizing recent progress with respect to
several challenges faced by such calculations. These lattice
calculations are based on a definition of TMDs through
hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for a lattice calculation. Results presented include data on the naively T-odd Sivers and Boer-Mulders effects, as well as the transversity and a worm-gear distribution. Correlating quark transverse momentum with impact
parameter, one can extract quark orbital angular momentum directly,including both the Ji as well as the Jaffe-Manohar definitions.