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

TL;DR

This study uses the SNO+ detector to search for invisible nucleon decay modes in water, setting new, more stringent limits on their partial lifetimes by analyzing nuclear de-excitation gamma rays.

Contribution

It provides the first comprehensive search for invisible nucleon decay modes in water with the SNO+ detector, improving existing lifetime limits by a factor of about 3.

Findings

New lower limits on nucleon decay lifetimes in water.

Improved constraints on invisible decay modes.

Enhanced detection sensitivity with SNO+.

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: $\tau(n\rightarrow inv) > 9.0\times10^{29}$ years, $\tau(p\rightarrow inv) > 9.6\times10^{29}$ years, $\tau(nn\rightarrow inv) > 1.5\times10^{28}$ years, $\tau(np\rightarrow inv) > 6.0\times10^{28}$ years, and $\tau(pp\rightarrow inv) > 1.1\times10^{29}$ years at 90\% Bayesian credibility level (with a prior uniform in rate). All but the ($nn\rightarrow inv$) results improve on existing limits by a factor of about 3.