Threshold pion electroproduction at large momentum transfers

Abstract

We consider pion electroproduction close to threshold for ${Q}^{2}$ in the region $1--10\text{ }\text{ }{\mathrm{GeV}}^{2}$ on a nucleon target. The momentum transfer dependence of the S-wave multipoles at threshold, ${E}_{0+}$ and ${L}_{0+}$, 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 ${F}_{2}(W,{Q}^{2})$ in the threshold region.