Renormalization of chiral two-pion exchange NN interactions with Delta-excitations: Central Phases and the Deuteron

TL;DR

This paper improves the theoretical modeling of neutron-proton interactions by explicitly including Delta-excitations, leading to better convergence and the ability to predict the deuteron bound state within an effective field theory framework.

Contribution

It introduces explicit Delta-excitations into chiral effective field theory for NN interactions, enhancing convergence and enabling deuteron bound state predictions at high cut-offs.

Findings

Enhanced convergence of np scattering results.

Successful reproduction of phase shifts for p ~ m_pi.

Prediction of deuteron bound state in the infinite cut-off limit.

Abstract

The renormalization of the chiral np interaction with Delta-excitations in intermediate states is considered at next-to-leading order (NLO) and next-to-next-to-leading order (N2LO) for central waves. The inclusion of the Delta-excitation as an explicit degree of freedom improves the convergence properties of the effective field theory results for np scattering with respect to Delta-less theory, and allows the existence of a deuteron bound state in the infinite cut-off limit. The 1S_0 singlet and 3S_1 triplet phase shifts reproduce data for p ~ m_pi. The role of spectral function regularization is also discussed.