Spin effects in the fragmentation of a transversely polarized quark
  An azimuthal dependence of pions produced in polarized Deep Inelastic Scattering, gamma^* - p(transv. polarized) -> pion + X, has been recently observed and might be related to the so-called Collins effect. We discuss in details, for a general spin configuration of the nucleon, the kinematics of the process and methods of extracting information on the fragmentation properties of a polarized quark. Assuming that the observed azimuthal dependence is indeed due to Collins effect, we derive a lower bound estimate for the size of the quark analysing power, which turns out to be large. 
M. Anselmino (1) and F. Murgia (2) ((1) University and INFN, Torino,   Italy, (2) INFN and University, Cagliari, Italy)