1212.3237 (C. Fernandez-Ramirez et al.)

Upper Energy Limit of Heavy Baryon Chiral Perturbation Theory in Neutral
Pion Photoproduction    [PDF]

C. Fernandez-Ramirez, A. M. Bernstein

We assess the energy limit up to which Heavy Baryon Chiral Perturbation Theory can be accurately applied to the process of neutral pion photoproduction from the proton by analyzing the latest data from the A2 and CB-TAPS collaborations at Mainz. We find that, within the current experimental status, the theory works up to $\sim$170 MeV. Above this energy the data call for further improvement in the theory such as the explicit inclusion of the $\Delta$(1232). We also find that data and multipoles can be well described up to $\sim$185 MeV with Taylor expansions in the partial waves up to first order in pion energy.

View original: http://arxiv.org/abs/1212.3237