Transversity in exclusive electroproduction of pseudoscalar mesons
  In this talk it is reported on an analysis of hard exclusive electroproduction of pseudoscalar mesons within the handbag approach. It is argued that recent measurements of pion electroproduction performed by HERMES and CLAS clearly indicate the occurence of strong contributions from transversely polarized photons. Within the handbag approach such transitions are described by the transversity GPDs accompanied by twist-3 pion wave functions. It is shown that this handbag approach leads to results on cross sections and single-spin asymmetries in fair agreement with experiment. The surprising result is that the pi0 cross section is dominated by gamma_T -> pion transitions. Predictions for other pseudoscalar meson channels are also discussed. 
P. Kroll
hep-ph