Δ isobars and nuclear saturation

A. Ekström, G. Hagen, T. D. Morris, T. Papenbrock, P. D. Schwartz
2018 Physical Review C  
We construct a nuclear interaction in chiral effective field theory with explicit inclusion of the Δ-isobar Δ(1232) degree of freedom at all orders up to next-to-next-to-leading order (NNLO). We use pion-nucleon (π N) low-energy constants (LECs) from a Roy-Steiner analysis of π N scattering data, optimize the LECs in the contact potentials up to NNLO to reproduce low-energy nucleon-nucleon scattering phase shifts, and constrain the three-nucleon interaction at NNLO to reproduce the binding
more » ... y and point-proton radius of ^4He. For heavier nuclei we use the coupled-cluster method to compute binding energies, radii, and neutron skins. We find that radii and binding energies are much improved for interactions with explicit inclusion of Δ(1232), while Δ-less interactions produce nuclei that are not bound with respect to breakup into α particles. The saturation of nuclear matter is significantly improved, and its symmetry energy is consistent with empirical estimates.
doi:10.1103/physrevc.97.024332 fatcat:64k6s4dy3rfc5dtfzquufdetfq