Stefan Scherer (Johannes Gutenberg University, Mainz)
We discuss the extended on-mass-shell scheme for manifestly Lorentz-invariant baryon chiral perturbation theory. We present a calculation of pion photo- and electro-production up to and including order q^4. The low-energy constants have been fixed by fitting experimental data in all available reaction channels. Our results can be accessed via a web interface, the so-called chiral MAID (http://www.kph.uni-mainz.de/MAID/chiralmaid, see the attached Figure). We explain how our program works and how it can be used for further analysis.