Nucleon-nucleon potentials from Delta-full chiral effective-field-theory and implications

TL;DR

This paper critically evaluates Delta-full chiral effective-field-theory NN potentials, revealing they have poor fit to scattering data despite seeming success in nuclear structure predictions, due to unrealistic P-wave state predictions.

Contribution

It identifies the limitations of current Delta-full chiral NN potentials, linking their poor scattering data fit to inaccuracies in P-wave state predictions, challenging their perceived accuracy.

Findings

Chi^2/datum of 60 for pp data below 100 MeV

Large deviations in P-wave state predictions, up to 40 times NNLO errors

Better nuclear structure predictions correlate with worse P-wave fits

Abstract

We closely investigate NN potentials based upon the Delta-full version of chiral effective field theory. We find that recently constructed NN potentials of this kind, which (when applied together with three-nucleon forces) were presented as predicting accurate binding energies and radii for a range of nuclei from A=16 to A=132 and providing accurate equations of state for nuclear matter, yield a chi^2/datum of 60 for the reproduction of the pp data below 100 MeV laboratory energy. This chi^2 is more than three times what the Hamada-Johnston potential of the year of 1962 achieved already some 60 years ago. We perceive this historical fact as concerning in view of the current emphasis on precision. We are able to trace the very large chi^2 as well as the apparent success of the potentials in nuclear structure to unrealistic predictions for P-wave states, in which the Delta-full NNLO potentials are off by up to 40 times the NNLO truncation errors. In fact, we show that, the worse the description of the P-wave states, the better the predictions in nuclear structure. Thus, these potentials cannot be seen as the solution to the outstanding problems in current miscroscopic nuclear structure physics.