On pi-pi Correlations in Polarized Quark Fragmentation Using the Linear   Sigma Model
  Using the linear sigma model to describe quark--pion interactions, we compute polarization asymmetries in quark fragmentation. We show that the effects of transverse quark polarizations appear in the correlation between the two leading pions in a jet produced by the fragmentation of a quark. Such asymmetries provide a window to the nature of chiral symmetry breaking in QCD. 
John C. Collins and Glenn A. Ladinsky