The pretzelosity distribution function and intrinsic motion of the   constituents in nucleon
  The pretzelosity distribution function $h_{1T}^\perp$ is studied in a covariant the quark-parton model which describes the structure of the nucleon in terms of 3D quark intrinsic motion. This relativistic model framework supports the relation between helicity, transversity and pretzelosity observed in other relativistic models {\sl without} assuming SU(6) spin-flavor symmetry. Numerical results and predictions for SIDIS experiments are presented. 
A.V. Efremov, P. Schweitzer, O.V. Teryaev, P. Zavada