  The exclusive electroproduction of pi+ mesons was studied with the Hermes
spectrometer at the DESY laboratory by scattering 27.6 GeV positron and
electron beams off an internal hydrogen gas target. The virtual-photon cross
sections were measured as a function of the Mandelstam variable t and the
squared four momentum -Q^2 of the exchanged virtual photon. A model calculation
based on Generalized Parton Distributions is in fair agreement with the data at
low values of |t| if power corrections are included. A model calculation based
on the Regge formalism gives a good description of the magnitude and the t and
Q^2 dependences of the cross section.
