Chiral uncertainties in ab initio nucleon-nucleus elastic scattering

TL;DR

This paper explores how uncertainties in chiral effective nucleon-nucleon interactions affect ab initio calculations of nucleon-nucleus elastic scattering, providing a systematic uncertainty quantification for light nuclei.

Contribution

It introduces a method to systematically quantify chiral interaction uncertainties in ab initio nucleon-nucleus scattering calculations using the Watson approach.

Findings

Uncertainty quantification reveals significant effects on scattering observables.

Chiral truncation errors are estimated at different orders in the nucleon-nucleon potential.

Elastic scattering predictions for light nuclei are analyzed across a range of energies.

Abstract

The effective interaction between a nucleon and a nucleus is one of the most important ingredients for reaction theories. Theoretical formulations were introduced early by Feshbach and Watson, and efforts of deriving and computing those `optical potentials' in a microscopic fashion have a long tradition. However, only recently the leading order term in the Watson multiple scattering approach could be calculated fully {\it ab initio}, meaning that the same nucleon-nucleon (NN) interaction enters both the structure as well as the reaction pieces on equal footing. This allows the uncertainties from the underlying chiral effective NN interaction to be systematically explored in nucleon-nucleus elastic scattering observables. In this contribution the main ingredients for arriving at the {\it ab initio} leading order of the effective nucleon-nucleus interaction in the Watson approach will be reviewed. Concentrating on one specific chiral NN interaction from the LENPIC collaboration and light nuclei with a 0$^+$ ground state, the leading order nucleon-nucleus interaction is calculated using up to the third chiral order (N2LO) in the nucleon-nucleon potential, and elastic scattering observables are extracted. Then pointwise as well as correlated uncertainty quantification is used for the estimation of the chiral truncation error. Elastic scattering observables for $^4$He, $^{12}$C, and $^{16}$O for between 65 and 200 MeV projectile energy will be analyzed.