Prediction of (p,n) Charge-Exchange Reactions with Uncertainty Quantification

TL;DR

This paper assesses the uncertainties in charge-exchange reaction predictions caused by optical potential models, highlighting the need for better constraints to reliably connect reactions to nuclear structure and forces.

Contribution

It introduces a Bayesian framework to quantify uncertainties in (p,n) charge-exchange reaction models, comparing phenomenological and microscopic optical potentials.

Findings

Charge-exchange cross sections are well reproduced by modern optical potentials.

Uncertainties in optical potentials lead to large uncertainties in predicted cross sections.

Charge-exchange reactions are sensitive probes for constraining nuclear forces.

Abstract

Background: Charge-exchange reactions are a powerful tool for exploring nuclear structure and nuclear astrophysics, however, a robust charge-exchange reaction theory with quantified uncertainties is essential to extracting reliable physics. Purpose: The goal of this work is to determine the uncertainties due to optical potentials used in the theory for charge-exchange reactions to isobaric analogue states. Method: We implement a two-body reaction model to study (p,n) charge-exchange transitions and perform a Bayesian analysis. We study the (p,n) reaction to the isobaric analog states of $^{14}$C, $^{48}$Ca, and $^{90}$Zr targets over a range of beam energies. We compare predictions using standard phenomenological optical potentials with those obtained microscopically. Results: Charge-exchange cross sections are reasonably reproduced by modern optical potentials. However, when uncertainties in the optical potentials are accounted for, the resulting predictions of charge-exchange cross sections have very large uncertainties. Conclusions: The charge-exchange reaction cross section is strongly sensitive to the input interactions, making it a good candidate to further constrain nuclear forces and aspects of bulk nuclear matter. However, further constraints on the optical potentials are necessary for a robust connection between this tool and the underlying isovector properties of nuclei.