Novel chiral Hamiltonian and observables in light and medium-mass nuclei

Abstract

A novel parameterisation of a Hamiltonian based on chiral effective field\ntheory is introduced. Specifically, three-nucleon operators at\nnext-to-next-to-leading order are combined with an existing (and successful)\ntwo-body interaction containing terms up to next-to-next-to-next-to-leading\norder. The resulting potential is labelled $N\\!N\\!$+$3N\\text{(lnl)}$. The\nobjective of the present work is to investigate the performance of this new\nHamiltonian across light and medium-mass nuclei. Binding energies, nuclear\nradii and excitation spectra are computed using no-core shell model and\nself-consistent Green's function approaches. Calculations with\n$N\\!N\\!$+$3N\\text{(lnl)}$ are compared to two other representative Hamiltonians\ncurrently in use, namely NNLO$_{\\text{sat}}$ and the older $N\\!N\\!$+$3N(400)$.\nOverall, the performance of the novel interaction is very encouraging. In light\nnuclei, total energies are generally in good agreement with experimental data.\nKnown spectra are also well reproduced with a few notable exceptions. The good\ndescription of ground-state energies carries on to heavier nuclei, all the way\nfrom oxygen to nickel isotopes. Except for those involving excitation processes\nacross the $N=20$ gap, which is overestimated by the new interaction, spectra\nare of very good quality, in general superior to those obtained with\nNNLO$_{\\text{sat}}$. Although largely improving on $N\\!N\\!$+$3N(400)$ results,\ncharge radii calculated with $N\\!N\\!$+$3N\\text{(lnl)}$ still underestimate\nexperimental values, as opposed to the ones computed with NNLO$_{\\text{sat}}$\nthat successfully reproduce available data on nickel. On the whole, the new\ntwo- plus three-nucleon Hamiltonian introduced in the present work represents a\npromising alternative to existing nuclear interactions.\n