Hard exclusive electroproduction of pions

We investigate the exclusive electroproduction of pi(+) mesons from nucleon s. To leading-twist, leading-order cu, accuracy, the corresponding producti on amplitude can be decomposed into pseudovector and pseudoscalar parts. Bo th can be expressed in terms of quark double distribution functions of the nucleon. While the pseudovector contribution is connected to ordinary polar ized quark distributions, the pseudoscalar Dart can be related to one-pion t-channel exchange. We observe that the pseudovector part of the production amplitude is important at x(Bj) < 0.1. On the other hand, for 0.1 < x(Bj) < 0.4, contributions from one-pion exchange dominate.