Search for neutrinoless double-beta decay in Xe136 with EXO-200

Abstract

We report on a search for neutrinoless double-beta decay of Xe136 with EXO-200. No signal is observed for an exposure of 32.5 kgyr, with a background of $\sim 1.5 \times 10^{-3} \text{kg}^{-1} \text{yr}^{-1} \text{keV}^{-1}$ in the $\pm 1\sigma$ region of interest. This sets a lower limit on the half-life of the neutrinoless double-beta decay $T_{1/2}^{0vBB}(^{136}Xe) >1.6\times 10^{25} \text{yr}$ (90% C.L.), corresponding to effective Majorana masses of less than 140-380 meV, depending on the matrix element calculation.