Measurement of the p(γ,π^{0}) cross section at threshold

Abstract

Differential and absolute cross sections for the reaction p(\ensuremath{\gamma},${\mathrm{\ensuremath{\pi}}}^{0}$) have been measured with energy-defined photons in the threshold region (${\mathit{E}}_{\ensuremath{\gamma}}$=131.4--157.2 MeV). The ${\mathit{E}}_{0+}$ amplitude has been extracted out of the data. The values found are in disagreement with predictions of low-energy theorems.