NEUTRAL PION-PHOTOPRODUCTION FROM THE PROTON NEAR-THRESHOLD

Differential and total cross sections for the photoproduction of neutr al pions from the proton have been measured for incident photon energi es from 140-270 MeV, using the photon spectrometer TAPS at the tagged photon beam of the 855 MeV Mainz Microtron. The energy dependence of t he s- and p-wave multipoles close to threshold was deduced from a mult ipole fit and a multipole analysis. The extracted s-wave amplitude E(0 +) at threshold is found to be significantly smaller than the predicti on of the classical low energy theorems, but is in reasonable agreemen t with the chiral perturbation theory.