$\mathbf{\beta}$-delayed proton emission from $\mathbf{^{11}}$Be in effective field theory*

We investigate the rare decay of $^{11}$Be into $^{10}$Be $+$ $p$ $+$ $e^-$ $+$ $\bar{\nu}_e$ using Halo effective field theory (Halo EFT), thereby describing the process of beta-delayed proton emission. The branching ratio for this decay mode in $^{11}$Be remains an important unsolved problem. Here, we will consider the weak decay of the valence neutron of the halo nucleus $^{11}$Be into the continuum for the first time within Halo EFT. We assume a shallow 1/2$^+$ resonance in the $^{10}$Be$-p$ system with an energy and width consistent with a recent experiment. Our results show that the experimental measurements of branching ratio and resonance parameters are consistent with each other. Thus, no exotic mechanism (such as beyond the standard model physics) is needed to explain the experimental decay rate.