Improved search for invisible modes of nucleon decay in water with the SNO+ detector

Abstract

This paper reports results from a search for single and multi-nucleon disappearance from the ${}^{16}$O nucleus in water within the \snoplus{} detector using all of the available data. These so-called "invisible" decays do not directly deposit energy within the detector but are instead detected through their subsequent nuclear de-excitation and gamma-ray emission. New limits are given for the partial lifetimes: $\ddot{I}„(n\to inv)>9.0\times 10^{29}$ years, $\ddot{I}„(p\to inv)>9.6\times 10^{29}$ years, $\ddot{I}„(nn\to inv)>1.5\times 10^{28}$ years, $\ddot{I}„(np\to inv)>6.0\times 10^{28}$ years, and $\ddot{I}„(pp\to inv)>1.1\times 10^{29}$ years at 90\% Bayesian credibility level (with a prior uniform in rate). All but the ($nn\to inv$) results improve on existing limits by a factor of about 3.