Compton scattering from the proton at fourth order in the chiral expansion

We present calculations of differential cross sections for Compton scattering from the proton, using amplitudes calculated to fourth order in heavy baryon chiral perturbation theory. We compare with available data up to 200 MeV. We find that the agreement for angles up to 90° is very good over the whole energy range, but that at more backward angles the agreement decreases above about 100 MeV and fails completely above the photoproduction threshold.