Two-neutrino double electron capture of ^{124}Xe in the first LUX-ZEPLIN exposure

The broad physics reach of the LUX-ZEPLIN (LZ) experiment covers rare phenomena beyond the direct detection of dark matter. We report precise measurements of the extremely rare decay of ^{124}Xe through the process of two-neutrino double electron capture (2\nu2EC), utilizing a 1.39\,\mathrm{kg} \times \mathrm{yr} isotopic exposure from the first LZ... Show more