# ${{\boldsymbol e}^{-}}$ 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.

# ${{\boldsymbol e}}$ $\rightarrow$ ${{\boldsymbol \nu}_{{e}}}{{\boldsymbol \gamma}}$ and astrophysical limits INSPIRE search

VALUE (yr) CL% DOCUMENT ID TECN  COMMENT
$\bf{>6.6 \times 10^{28}}$ 90
 2015 B
BORX ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$
• • • We do not use the following data for averages, fits, limits, etc. • • •
$>1.2 \times 10^{24}$ 90
 2017
HPGE electron decay to invisible
$>1.22 \times 10^{26}$ 68 1
 2007
CNTR ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$
$>4.6 \times 10^{26}$ 90
 2002
BORX ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$
$>3.4 \times 10^{26}$ 68
 2000 B
DAMA ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$ , liquid Xe
$>3.7 \times 10^{25}$ 68
 1995 B
CNTR ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$
$>2.35 \times 10^{25}$ 68
 1993
CNTR ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$ , ${}^{76}\mathrm {Ge}$ detector
$>1.5 \times 10^{25}$ 68
 1986
CNTR ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$
$>1 \times 10^{39}$ 2
 1985
ASTR Astrophysical argument
$>3 \times 10^{23}$ 68
 1983 B
CNTR ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$
1  The authors of A. Derbin et al, arXiv:0704.2047v1 argue that this limit is overestimated by at least a factor of 5.
2  ORITO 1985 assumes that electromagnetic forces extend out to large enough distances and that the age of our galaxy is $10^{10}$ years.
Conservation Laws:
 ELECTRIC CHARGE ($\mathit Q$)
References:
 ABGRALL 2017
PRL 118 161801 New limits on Bosonic Dark Matter, Solar Axions, Pauli Exclusion Principle Violation, and Electron Decay from the Majorana Demonstrator
 AGOSTINI 2015B
PRL 115 231802 A Test of Electric Charge Conservation with Borexino
 KLAPDOR-KLEINGROTHAUS 2007
PL B644 109 A New Experimental Limit for the Stability of the Electron
 BACK 2002
PL B525 29 Search for Electron Decay Mode ${{\mathit e}}$ $\rightarrow$ ${{\mathit \gamma}}{+}$ ${{\mathit \nu}}$ with Prototype of BOREXINO Detector
 BELLI 2000B
PR D61 117301 Quest for Electron Decay ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}_{{e}}}{{\mathit \gamma}}$ with a Liquid Xenon Scintillator
 AHARONOV 1995B
PR D52 3785 New Laboratory Bounds on the Stability of the Electron
 BALYSH 1993
PL B298 278 New Experimental Limit for Electron Decay and Charge Conservation
 AVIGNONE 1986
PR D34 97 New Experimental Limit on the Stability of the Electron
 ORITO 1985
PRL 54 2457 Can Universe be Charged?
 BELLOTTI 1983B
PL 124B 435 A New Experimental Limit on Electron Stability