Higher twist contributions from the direct pion coupling in e+e- annihilation, photoproduction and π-p Drell-Yan

Calculations are presented of normalized higher twist contributions in three processes in which the central sub-processes are related by crossing: the production of hadrons at high transverse momentum relative to the thrust axis in e+e-annihilation, photoproduction of high transverse momentum pions from a proton target, and high transverse momentum lepton pair production in π-p collisions. The last of these is most interesting, not only because the higher twist contribution is significant, but also the QCD interpretation of the data is uncertain. (author)