The Quark-Quark Correlator: Theory and Phenomenology
  New properties of the quark correlator are found via equations of motion. As a first result, approximate relations can be established among the "soft" functions; one such relation may help in determining the quark transversity in a nucleon. Secondly, the Q^2 dependence of the T-odd functions is deduced; the result is compared to unpolarized Drell-Yan data. Lastly, important remarks are made about the contributions to g_2(x). 
E. Di Salvo