Estimate of the Collins function in a chiral invariant approach
  We estimate the Collins function at a low energy scale by calculating the fragmentation of a quark into a pion at the one-loop level in the chiral invariant model of Manohar and Georgi. We give a useful parametrization of our results and we briefly discuss different spin and/or azimuthal asymmetries containing the Collins function and measurable in semi-inclusive DIS and e+ e- annihilation 
A. Bacchetta, R. Kundu, A. Metz, P.J. Mulders