Enhancement of deltaful two-pion exchange nuclear forces

Abstract

The role of the delta isobar degrees of freedom in nucleon–nucleon scattering is revisited. We attempt to understand why the dimensionally regularized two-pion exchanges with the explicit delta isobar is much stronger than the ones with spectral function regularization. When the cut-off value of spectral function regularization is varied, the isoscalar central component exhibits a rather large cut-off variation. This reveals a surprisingly large numerical factor of the deltaful two-pion exchange potentials. The power counting is adjusted accordingly and we discuss the results and how to improve upon this finding.