Modeling the transverse momentum dependent parton distributions

We review quark model calculations of the transverse momentum dependent parton distributions (TMDs). For the T-even TMDs, we discuss the physical origin of model relations which hold in a large class of quark models. For the T-odd TMDs we review results in a light-cone constituent quark model (CQM) with the final state interaction effects generated via single-gluon exchange mechanism. As phenomenological application, we show the good agreement between results in the light-cone CQM and available experimental data for the Collins asymmetry.
Comment: 8 pages, 2 figures, 2 tables; invited talk at "The 4th Workshop on Exclusive Reactions at High Momentum Transfer", Jefferson Lab., May 18-21, 2010