Two-pion exchange contributions to the nucleon-nucleon interaction from the Roper resonance

We derive the long-range components of the nucleon-nucleon (NN) two-pion-exchange potential with an intermediate Roper resonance. Leading-order interactions in heavy-baryon chiral perturbation theory are considered. To assess the Roper contributions in a unified framework, we include the leading contributions from the Delta resonance, as well as mixed Delta-Roper effects. NN phase shifts with orbital angular momentum L≥ 2 are calculated in first-order perturbation theory and compared to those obtained without the Roper resonance. We find that the Delta sets the dominant scale of the resonance-induced corrections, while the Roper-dependent effects are smaller, strongly channel dependent, and most visible in the D waves.