Ab initio calculation of the $\beta$-decay from $^{11}$Be to a p${+}^{10}$Be resonance

TL;DR

This study uses ab initio methods to calculate the beta-delayed proton emission in $^{11}$Be, revealing that an unobserved proton resonance likely explains the unexpectedly large branching ratio observed experimentally.

Contribution

The paper introduces a first-principles calculation of the $^{11}$Be beta decay process, focusing on the role of a proposed proton resonance in $^{11}$B to explain experimental anomalies.

Findings

Calculated branching ratio $b_p = (1.3 extpm0.5) imes10^{-6}$

Identified a potential unobserved proton resonance in $^{11}$B

Provided insight into the nature of the large experimental branching ratio

Abstract

The exotic $\beta$-delayed proton emission is calculated in $^{11}$Be from first principles using chiral two- and three-nucleon forces. To investigate the unexpectedly-large branching ratio measured in [PRL 123, 082501 (2019)] we calculate the proposed $(1/2^+,1/2)$ proton resonance in $^{11}$B using the no-core shell model with continuum. This calculation helps to address whether this enhancement is caused by unknown dark decay modes or an unobserved proton resonance. We report a branching ratio of $b_p = (1.3\pm0.5)\times10^{-6}$, suggesting that its unexpectedly-large value is caused by an unobserved proton resonance in $^{11}$B.