# Search for Tri-Nucleon Decay in the Majorana Demonstrator

## TL;DR

This paper reports the first experimental limits on tri-nucleon decay modes in germanium isotopes using the Majorana Demonstrator, an ultra low-background detector primarily designed for neutrinoless double-beta decay searches.

## Contribution

It provides the first limits on tri-nucleon decay modes in $^{76}$Ge, expanding the search for exotic physics beyond previous experiments.

## Key findings

- Half-life limit of 4.9 x 10^{25} years for $^{76}$Ge(ppn) decay.
- Half-life limit of 4.7 x 10^{25} years for $^{76}$Ge(ppp) decay.
- Half-life limit of 7.5 x 10^{24} years for invisible tri-proton decay mode.

## Abstract

The Majorana Demonstrator is an ultra low-background experiment searching for neutrinoless double-beta decay in $^{76}$Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. We present the first limits for tri-nucleon decay-specific modes and invisible decay modes for Ge isotopes. We find a half-life limit of $4.9 \times 10^{25}$ yr for the decay $^{76}{\rm Ge(ppn)} \to {}^{73}{\rm Zn}\ e^+\pi^+$ and $4.7\times10^{25}$ yr for the decay $^{76}{\rm Ge(ppp)} \to ^{73}{\rm Cu}\ e^+\pi^+\pi^+$. The half-life limit for the invisible tri-proton decay mode of $^{76}$Ge was found to be $7.5\times10^{24}$ yr.