Nucleon decay in the nucleus

Abstract

We estimate the change in the baryon-number-violating nucleon lifetime inside a nucleus, compared to the freespace decay of the nucleon. For the decay modes $p\ensuremath{\rightarrow}{e}^{+}{\ensuremath{\pi}}^{0}, {e}^{+}\ensuremath{\omega}$ and $n\ensuremath{\rightarrow}{e}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, we include the effects of pion or $\ensuremath{\omega}$ absorption and pion rescattering (including charge exchange). The rescattering effects are found to represent a correction of only a few percent or less to the total decay rate. The pion and $\ensuremath{\omega}$ absorption corrections depend sensitively on the nature of the nucleon-nucleon short-range correlations, varying from roughly 5 to 50% depending on the hard-core radius. These modes lead to the emission of fast nucleons and a displaced bump in the positron spectrum.