Models for TMDs and numerical methods
  We study the connection between the quark orbital angular momentum and the pretzelosity transverse-momentum dependent parton distribution function. We discuss the origin of this relation in quark models, identifying as key ingredient for its validity the assumption of spherical symmetry for the nucleon in its rest frame. Finally we show that the individual quark contributions to the orbital angular momentum obtained from this relation can not be interpreted as the intrinsic contributions, but include the contribution from the transverse centre of momentum which cancels out only in the total orbital angular momentum. 
B. Pasquini (Pavia U. and INFN, Pavia) and C. Lorce' (IPN and LPT,   Orsay)
hep-ph hep-ex