Threshold pion electroproduction at large momentum transfers

Abstract

We consider pion electroproduction close to threshold for Q2 in the region 1–10  GeV2 on a nucleon target. The momentum transfer dependence of the S-wave multipoles at threshold, E0+ and L0+, is calculated in the chiral limit using light-cone sum rules. Predictions for the cross sections in the threshold region are given taking into account P-wave contributions that, as we argue, are model independent to a large extent. The results are compared with the SLAC E136 data on the structure function F2(W,Q2) in the threshold region.