The width of the $\Delta$-resonance at two loop order in baryon chiral   perturbation theory
  We calculate the width of the delta resonance at leading two-loop order in baryon chiral perturbation theory. This gives a correlation between the leading pion-nucleon-delta and pion-delta couplings, which is relevant for the analysis of pion-nucleon scattering and other processes. 
Jambul Gegelia, Ulf-G. Mei{\ss}ner, Dmitrij Siemens, De-Liang Yao
hep-ph