Probing pretzelosity $h^{\perp}_{1T}$ via the polarized   proton-antiproton Drell-Yan process
  We show that the polarized proton-antiproton Drell-Yan process is ideal to probe the pretzelosity distribution ($h_{1T}^\perp$), which is one of the new transverse-momentum-dependent parton distributions of the nucleon. We present predictions of the $\cos(2\phi + \phi_a - \phi_b)$ asymmetry in the transversely polarized proton-antiproton Drell-Yan process at PAX kinematics and find that the results are significantly larger compared with those of the $\sin(3\phi_h - \phi_S)$ asymmetry in the semi-inclusive deep inelastic scattering process at HERMES, COMPASS, and JLab kinematics. We conclude that the $\cos(2\phi + \phi_a - \phi_b)$ asymmetry in the PAX experiment can probe the new physical quantity of the pretzelosity distribution. 
Jiacai Zhu, Bo-Qiang Ma
hep-ph hep-ex nucl-ex nucl-th