The chiral effective pion-nucleon Lagrangian of order p^4
  We construct the minimal effective chiral pion-nucleon SU(2) Lagrangian at fourth order in the chiral expansion. The Lagrangian contains 118 in principle measurable terms. We develop both the relativistic as well as the heavy baryon formulation of the effective field theory. For the latter, we also work out explicitly all 1/m corrections at fourth order. We display all relevant relations needed to find the linearly independent terms. 
Nadia Fettes, Ulf-G. Mei{\ss}ner, Martin Mojzis, Sven Steininger