Speaker
Prof.
simonetta liuti
(university of virginia)
Description
We discuss the canonical (Ji) and kinetic/mechanical (Jaffe and Manohar)
definitions of partonic orbital angular momentum (OAM). It was recently
shown by Hatta and Burkardt that the two definitions correspond to the
second moment in intrinsic k_T of the same generalized transverse momentum
distribution (GTMD), while they differ in their gauge link structure. At
the same time, as first observed by Polyakov, canonical orbital angular
momentum can be independently described in terms of a twist three generalized
parton distribution, which only a straight type of gauge link is allowed for.
Here we provide further insight into this problem by showing that the second
moment in k_T of the OAM twist two GTMD and twist three GPD, are connected
through a Wandzura Wilzceck type relation which generalizes the one originally
developed for the polarized twist three distribution, g_T. An important outcome
of the picture we provide is that the two different mechanisms for generating
partonic OAM can be both tested experimentally and validated by lattice
calculations. Additional calculations using the Reggeized Diquark model are
shown that provide an initial guidance for assessing the size of the various
contributions.
Author
Prof.
simonetta liuti
(university of virginia)
