Pion-nucleon scattering around the delta-isobar resonance

Bingwei Long
ECT*, Trento, Italy

Besides the nucleon, the pion and delta-isobar are important ingredients 
in low-energy strong interactions due to their light mass (pion) or small 
excitation above the nucleon (delta). Chiral EFT provides a powerful tool 
to include these three in nuclear physics. We develop a generalized 
version of heavy-baryon chiral perturbation theory for low-energy 
pion-nucleon scattering, so that both the threshold and delta resonance 
regions are described in a unified framework. P-wave phase shifts are 
calculated up to the third order in our power counting.