Projected sensitivity of the LUX-ZEPLIN experiment to the $0\nu\beta\beta$ decay of $^{136}$Xe

TL;DR

The LUX-ZEPLIN experiment is projected to have a sensitivity to neutrinoless double beta decay of $^{136}$Xe comparable to current limits, using its large xenon mass and planned exposure times.

Contribution

This paper provides the first sensitivity estimate for LZ's neutrinoless double beta decay search using its existing xenon mass without enrichment.

Findings

Projected median half-life sensitivity of 1.06×10^{26} years with 1000 live-days.

Enhanced sensitivity of 1.06×10^{27} years with enriched xenon.

LZ's sensitivity is comparable to current experimental constraints.

Abstract

The LUX-ZEPLIN (LZ) experiment will enable a neutrinoless double beta decay search in parallel to the main science goal of discovering dark matter particle interactions. We report the expected LZ sensitivity to $^{136}$Xe neutrinoless double beta decay, taking advantage of the significant ($>$600 kg) $^{136}$Xe mass contained within the active volume of LZ without isotopic enrichment. After 1000 live-days, the median exclusion sensitivity to the half-life of $^{136}$Xe is projected to be 1.06$\times$10$^{26}$ years (90% confidence level), similar to existing constraints. We also report the expected sensitivity of a possible subsequent dedicated exposure using 90% enrichment with $^{136}$Xe at 1.06$\times$10$^{27}$ years.