Baryon chiral perturbation theory: one loop and beyond

Matthias R. Schindler
The George Washington University

For energies below 1 GeV, perturbative calculations in the strong coupling of QCD are 
not meaningful. One of the theoretical tools to explore this energy region is the use 
of an effective field theory, chiral perturbation theory (ChPT). After giving an 
introduction to the underlying ideas of ChPT I will focus on the one-nucleon sector. 
With the development of new renormalization schemes the evaluation of contributions 
beyond one-loop order has become possible in a manifestly Lorentz-invariant 
formulation. I will describe two different approaches to higher-order calculations: 
the inclusion of additional degrees of freedom and the explicit calculation of 
two-loop diagrams. Results for the nucleon form factors and the nucleon mass will be 
presented. I will also discuss the connection to lattice QCD.