$\beta^-{\rm p}$ and $\beta^-\alpha$ decay of the $^{11}$Be neutron halo ground state

TL;DR

This paper investigates the beta-delayed proton and alpha decay of the $^{11}$Be neutron halo ground state using a continuum shell model, questioning the resonance explanation for the high decay rate.

Contribution

It applies the real-energy continuum shell model to analyze decay observables and challenges the resonance hypothesis for the large beta-delayed proton branching ratio.

Findings

Large $eta^-{ m p}$ branching ratio cannot be explained by a resonance within the model.

The model successfully describes Gamow-Teller decay rates for $eta^-$-delayed decays.

The resonance hypothesis for the decay rate is not supported by the model analysis.

Abstract

Beta-delayed proton emission from the neutron halo ground state of $^{11}$Be raised much attention due to the unusually high decay rate. It was argued that this may be due to the existence of a resonance just above the proton decay threshold. In this Letter, we use the lenses of real-energy continuum shell model to describe several observables including the Gamow-Teller rates for the $\beta^-$-delayed $\alpha$ and proton decays, and argue that, within our model, the large $\beta^-{\rm p}$ branching ratio cannot be reconciled with other data.