Exclusive photo- and electroproduction of mesons at large momentum   transfer
  We analyze the reactions gamma+p => M+B, with M B being either K+ Lambda, K+ Sigma0, or pi+ n, within perturbative QCD, allowing for diquarks as quasi-elementary constituents of baryons. The diquark-model parameters and the quark-diquark distribution amplitudes of the baryons are taken from previous investigations of electromagnetic baryon form factors and Compton- scattering off protons. Reasonable agreement with the few existing data at large momentum transfer is achieved if the asymptotic form (c x (1-x)) is chosen for the meson distribution amplitudes. 
G. Folberth, R. Rossmann and W. Schweiger