Renormalization of the chiral pion–nucleon Lagrangian beyond next–to–leading order

The complete renormalization of the generating functional for Green functions of quark currents between one–nucleon states in two flavor heavy baryon chiral perturbation theory is performed to order q4. We show how the heat kernel method has to be extended for operators orthogonal to the heavy fermion four–velocity. A method is developed to treat the multi–coincidence limit arising from insertions of dimension two (and higher) operators on internal baryon propagators in self–energy graphs. As examples, we study the divergences in the isoscalar magnetic moment and the scalar form factor of the nucleon. Work supported in part by DFG (grants Me 864-11/1, Schu 439-10/1), by funds provided by the Graduiertenkolleg ”Die Erforschung subnuklearer Strukturen der Materie” at Bonn University and by DAAD. email: [email protected] email: [email protected] Address after Nov. 1, 1998: Institut für Theoretische Physik, Universität Wien, A–1090 Wien, Austria. email: [email protected]