Near-threshold electroproduction of neutral pions on protons

The near-threshold electroproduction of neutral pions on protons is considered within the phenomenological model that is based on the hard-pion current algebra and which takes into consideration explicit chiral-symmetry breaking. The s-wave differential cross section at the threshold is found as a function of the squared momentum transfer k(2). The dependence of the s-wave multipole amplitudes ReE0+ and ReL0+ on the energy of the pi(0)p system near the threshold is obtained for low k(2) and for k(2) = 0.1 (GeV/c)(2). The results are compared with experimental data. The importance of explicit chiral-symmetry breaking is demonstrated.