${{\boldsymbol e}^{-}}$ MEAN LIFE $/$ BRANCHING FRACTION

A test of charge conservation. See the Note on Testing Charge Conservation and the Pauli Exclusion Principle'' following this section in our 1992 edition (Physical Review D45 S1 (1992), p.$~$VI.10).
Most of these experiments are one of three kinds: Attempts to observe (a)$~$the 255.5 keV gamma ray produced in ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}_{{e}}}{{\mathit \gamma}}$ , (b)$~$the (K)$~$shell x$~$ray produced when an electron decays without additional energy deposit, e.g., ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}_{{e}}}{{\overline{\mathit \nu}}_{{e}}}{{\mathit \nu}_{{e}}}$ (disappearance'' experiments), and (c)$~$nuclear de-excitation gamma rays after the electron disappears from an atomic shell and the nucleus is left in an excited state. The last can include both weak boson and photon mediating processes. We use the best ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}_{{e}}}{{\mathit \gamma}}$ limit for the Summary Tables.
Note that we use the mean life rather than the half life, which is often reported.

Disappearance and nuclear-de-excitation experiments INSPIRE search

VALUE (yr) CL% DOCUMENT ID TECN  COMMENT
$\bf{>6.4 \times 10^{24}}$ 68 1
 1999 B
DAMA De-excitation of ${}^{129}\mathrm {Xe}$
• • • We do not use the following data for averages, fits, limits, etc. • • •
$>4.2 \times 10^{24}$ 68
 1999
DAMA Iodine L-shell disappearance
$>2.4 \times 10^{23}$ 90 2
 1999 D
DAMA De-excitation of ${}^{127}\mathrm {I}$ (in NaI)
$>4.3 \times 10^{23}$ 68
 1995 B
CNTR Ge K-shell disappearance
$>2.7 \times 10^{23}$ 68
 1991
CNTR ${}^{}\mathrm {Ge}$ K-shell disappearance
$>2 \times 10^{22}$ 68
 1983 B
CNTR ${}^{}\mathrm {Ge}$ K-shell disappearance
1  BELLI 1999B limit on charge nonconserving ${{\mathit e}^{-}}$ capture involving excitation of the 236.1 keV nuclear state of ${}^{129}\mathrm {Xe}$; the 90$\%$ CL limit is $3.7 \times 10^{24}~$yr. Less stringent limits for other states are also given.
2  BELLI 1999D limit on charge nonconserving ${{\mathit e}^{-}}$ capture involving excitation of the 57.6 keV nuclear state of ${}^{127}\mathrm {I}$. Less stringent limits for the other states and for the state of ${}^{23}\mathrm {Na}$ are also given.
References:
 BELLI 1999
PL B460 236 New Experimental Limit on the Electron Stability and NonPaulian Transitions in Iodine Atoms
 BELLI 1999B
PL B465 315 Charge Non-conservation Restrictions from the Nuclear Levels Excitation of ${}^{129}\mathrm {Xe}$ Induced by the Electron's Decay on the Atomic Shell
 BELLI 1999D
PR C60 065501 New Limits on the Nuclear Levels Excitation of ${}^{127}\mathrm {I}$ and ${}^{23}\mathrm {Na}$ During Charge Nonconservation
 AHARONOV 1995B
PR D52 3785 New Laboratory Bounds on the Stability of the Electron
 REUSSER 1991
PL B255 143 Limits on Cold Dark Matter from the Gotthard ${}^{}\mathrm {Ge}$ Experiment
 BELLOTTI 1983B
PL 124B 435 A New Experimental Limit on Electron Stability