Rejection of Evidence for Nonzero Neutrino Rest Mass from Double Beta Decay

Abstract

Previous evidence from double beta decay (DBD) of ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$ and ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ required neutrinoless DBD involving a neutrino rest mass of ${\hat{m}}_{\nu }\sim 34$ eV (∼10 eV in the most recent theoretical treatment) or else a strong violation of lepton-number conservation ($\eta \ne 0$) due to a ($V+A$) admixture. The DBD rate ratio of ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$ and ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ has been redetermined. The present result is consistent with ${\hat{m}}_{\nu }=\eta =0\mathrm{}$. The experimental limits still allow Majorana decay at levels of ${\hat{m}}_{\nu }<~5.6$ eV or $\eta <~2.4\times {10}^{-5\mathrm{}}$ (95% confidence). The DBD half-life for ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$ is $T_{\frac{1}{2}}\left({}_{}{}^{128}{}_{}{}^{}\mathrm{Te}\right)>\mathrm{}8\mathrm{}\times {10}^{24}$ yr ($2\sigma$).