# Searches for Double Beta Decay of $^{134}$Xe with EXO-200

## TL;DR

This paper reports on searches for double beta decay of $^{134}$Xe using the EXO-200 detector, setting new lower limits on decay half-lives that significantly improve previous constraints, with implications for neutrino physics.

## Contribution

The study provides the first competitive limits on $^{134}$Xe double beta decay using a large liquid xenon detector, surpassing previous experimental bounds by large factors.

## Key findings

- Lower limit for two-neutrino double beta decay: >8.7×10^{20} yr
- Lower limit for neutrinoless double beta decay: >1.1×10^{23} yr
- Improved constraints by factors of nearly 10^5 and 2, respectively

## Abstract

Searches for double beta decay of $^{134}$Xe were performed with EXO-200, a single-phase liquid xenon detector designed to search for neutrinoless double beta decay of $^{136}$Xe. Using an exposure of $29.6\text{ kg}\!\cdot\!\text{yr}$, the lower limits of $\text{T}_{1/2}^{2\nu\beta\!\beta}>8.7\cdot10^{20}\text{ yr}$ and $\text{T}_{1/2}^{0\nu\beta\!\beta}>1.1\cdot10^{23}\text{ yr}$ at 90% confidence level were derived, with corresponding half-life sensitivities of $1.2\cdot10^{21}\text{ yr}$ and $1.9\cdot10^{23}\text{ yr}$. These limits exceed those in the literature for $^{134}$Xe, improving by factors of nearly $10^{5}$ and 2 for the two antineutrino and neutrinoless modes, respectively.