Non-Standard Time Reversal and Transverse Single-Spin Asymmetries
  A system of quarks interacting with chiral fields is shown to provide a physical realization of a "non-standard" time reversal for particle multiplets which mixes the multiplet components. We argue that, if the internal structure of the nucleon is governed by a chiral dynamics, the so-called T-odd quark distribution functions are not forbidden by time-reversal invariance and hence might be non vanishing. This agrees with some other recent results. From a phenomenological point of view, this would give rise to single-spin asymmetries in inclusive processes involving a transversely polarized nucleon: in particular, in pion lepto- and hadro-production and in Drell-Yan processes. 
M. Anselmino (1), V. Barone (2,1), A. Drago (3), F. Murgia (4) ((1)   University and INFN, Torino, Italy, (2) University and...