On wave function renormalization and related aspects in heavy fermion   effective field theories
  We reconsider the question of wave function renormalization in heavy fermion effective field theories. In particular, we work out a simple and efficient scheme to define the wave function renormalization with respect to the lowest order heavy fermion propagator. The method presented is free of a set of ambiguities which arise in heavy fermion effective field theories. In this context, we discuss the approaches used in the literature so far. We also calculate the fourth order pion mass contribution to the nucleon mass shift and discuss the tree and loop contributions to the electric Sachs form factor of the nucleon. 
Sven Steininger, Ulf-G. Mei{\ss}ner and Nadia Fettes