Application of the microscopic optical potential of chiral effective field theory in astrophysical neutron-capture reactions

TL;DR

This paper applies a microscopic optical potential derived from chiral effective field theory to astrophysical neutron-capture reactions, demonstrating good agreement with experimental data and exploring uncertainties in reaction rates for neutron-rich nuclei.

Contribution

It is the first application of the WLH microscopic optical potential to astrophysical neutron-capture reactions, providing insights into isospin dependence and reaction rate uncertainties.

Findings

Good description of experimental neutron-capture cross sections.

Calculated reaction rates for nuclei with 26≤Z≤84.

Uncertainty separation around isospin asymmetry of 0.28.

Abstract

A state-of-the-art microscopic global nucleon-nucleus optical potential has been developed by Whitehead, Lim, and Holt (WLH) within the framework of many-body perturbation theory, incorporating realistic nuclear interactions derived from chiral effective field theory. Given its potentially greater predictive power for reactions involving exotic isotopes, we apply it to the calculations of astrophysical neutron-capture reactions for the first time, which are particularly important to the nucleosynthesis of elements heavier than iron. It is found that this potential provides a good description of experimental known neutron-capture cross sections and Maxwellian-averaged cross sections. For unstable neutron-rich nuclei, we comprehensively calculate the neutron-capture reaction rates for all nuclei with $26\leq Z\leq84$, located between the valley of stability and the neutron drip line, using the backward-forward Monte Carlo method with the $f_{rms}$ deviation as the $\chi^2$ estimator. The results reveal a noticeable separation in the uncertainty of rates around an isospin asymmetry of 0.28 under the constraint $f_{rms} \leq 1.56$. This highlights the critical role of isospin dependence in optical potentials and suggests that future developments of the WLH potential may pay special attention to the isospin dependence.