Precise pion electroproduction in the p(e,e'pi(+))n reaction at W=1125 MeV

The reaction e+p --> e+pi(+)+n, at c.m. energy W = 1125MeV and momentum transfer Q(2) = 0.117GeV(2)/c(2) has been measured. The transverse and longitudinal structure functions have been separated by varying the polarization of the virtual photon (Rosenbluth plot) with a 3 to 4% error. In addition the longitudinal-transverse interference term has been determined measuring the right-left asymmetry with an accuracy of 3%. The experimental data are compared to model calculations, and the sensitivity of the results to the axial and pion formfactors is discussed.