New laboratory bounds on the stability of the electron

A set of two natural abundance Ge detectors of 1.1 kg each, located in the Homestake mine, and one small, 0.253 kg, Ge detector operating in the Canfranc railway tunnel in Spain, have been used to obtain bounds on the stability of the electron against the decay modes ${\mathit{e}}^{\mathrm{-}}$→γ${\nu }_2$ and ${\mathit{e}}^{\mathrm{-}}$→${\nu }_{\mathit{e}}$ ${\nu }_{\mathit{e}}$ν${\mathrm{¯}}_{\mathit{e}}$. The bounds on the mean lives are τ(γ${\nu }_{\mathit{e}}$)>3.7(2.1)×${10}^{25}$ yR, 68% (90%) C.L. and τ(${\nu }_{\mathit{e}}$ ${\nu }_{\mathit{e}}$ν${\mathrm{¯}}_{\mathit{e}}$)>4.3(2.6)×${10}^{23}$ yr, 68% (90%) /C.L. which are at present the most stringent laboratory limits for these decays. The theoretical controversy concerning the relevance of such data to fundamental tests of charge conservation is also considered.