Pion-nucleon elastic scattering amplitude within covariant baryon chiral   perturbation theory up to $O(p^4)$ level
  The $O(p^4)$ calculation on pion-nucleon elastic scattering amplitude in EOMS scheme within covariant baryon chiral perturbation theory is reviewed. Numerical fits to partial wave amplitudes up to $\sqrt{s}=1.13$ GeV and 1.20 GeV are performed and the results are compared with previous studies. 
Yun-hua Chen, De-liang Yao, H. Q. Zheng
hep-ph