The Roper resonance in a finite volume

Daniel Severt,Ulf-G Meißner

Figure 1. One-loop diagrams contributing to the Roper mass at third chiral order. Thick solid, dashed, solid, and solid double lines refer to the Roper resonance, pions, nucleons, and delta baryon states, respectively. The vertices denoted by a filled dot refer to insertions from the first order chiral Lagrangian.