Complex-mass scheme and resonances in EFT
  The complex-mass scheme (CMS) provides a consistent framework for dealing with unstable particles in quantum field theory and has been successfully applied to various loop calculations. As applications of the CMS in chiral effective field theory we consider the form factor of the pion in the time-like region and the magnetic moment of the Roper resonance. 
T. Bauer, D. Djukanovic, J. Gegelia, S. Scherer and L. Tiator
nucl-th