Test of low-energy theorems for p(\vec{gamma},π^{0})p in the threshold region

Abstract

The photon asymmetry in the reaction p(\vecγ,π^{0})p close to threshold has been measured for the first time with the photon spectrometer TAPS using linearly polarized photons from the tagged-photon facility at the Mainz Microtron MAMI. The total and differential cross sections were also measured simultaneously with the photon asymmetry. This allowed determination of the S-wave and all three P-wave amplitudes. The low-energy theorems based on the parameter-free third-order calculations of heavy-baryon chiral perturbation theory for P1 and P2 agree with the experimental values.

14 pages Latex including 3 figures and 1 table