Lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs)

¹ Department of Physics, New Mexico State University, Las Cruces, NM 88003, USA
² Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany
³ Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
⁴ Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
⁵ Bergische Universität Wuppertal, 42119 Wuppertal, Germany
⁶ IAS, Jülich Supercomputing Centre, Forschungszentrum Jülich, 52425 Jülich, Germany
⁷ Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
⁸ Theory Center, Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA

^a e-mail: engel@nmsu.edu

Published online: 21 March 2016

Abstract

An ongoing program of evaluating TMD observables 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. Data on the naively T-odd Sivers and Boer-Mulders effects as well as the transversity TMD are presented.