LIMIT ON MUONIUM $\rightarrow$ ANTIMUONIUM CONVERSION

Forbidden by lepton family number conservation.

$\mathit R_{\mathit g}$ = $\mathit G_{\mathit C}$ $/$ $\mathit G_{\mathit F}$

INSPIRE   PDGID:
S004MC
The effective Lagrangian for the ${{\mathit \mu}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \mu}^{-}}{{\mathit e}^{+}}$ conversion is assumed to be

$\cal L$ = 2${}^{−1/2}$ $\mathit G_{\mathit C}$ [${{\overline{\mathit \psi}}_{{{\mu}}}}{{\mathit \gamma}_{{{\lambda}}}}$ (1 $−$ ${{\mathit \gamma}}_{5}$) ${{\mathit \psi}_{{{e}}}}$] [${{\overline{\mathit \psi}}_{{{\mu}}}}{{\mathit \gamma}_{{{\lambda}}}}$ (1 $−$ ${{\mathit \gamma}}_{5}$) ${{\mathit \psi}_{{{e}}}}$] $+$ h.c.

The experimental result is then an upper limit on $\mathit G_{\mathit C}/\mathit G_{\mathit F}$, where $\mathit G_{\mathit F}$ is the Fermi coupling constant.
VALUE CL% EVTS DOCUMENT ID TECN CHG  COMMENT
$\bf{<0.0030}$ 90 1 1
WILLMANN
1999
SPEC + ${{\mathit \mu}^{+}}$ at 26 GeV/$\mathit c$
• • We do not use the following data for averages, fits, limits, etc. • •
$<0.14$ 90 1 2
GORDEEV
1997
SPEC + JINR phasotron
$<0.018$ 90 0 3
ABELA
1996
SPEC + ${{\mathit \mu}^{+}}$ at 24 MeV
$<6.9$ 90
NI
1993
CBOX LAMPF
$<0.16$ 90
MATTHIAS
1991
SPEC LAMPF
$<0.29$ 90
HUBER
1990B
CNTR TRIUMF
$<20$ 95
BEER
1986
CNTR TRIUMF
$<42$ 95
MARSHALL
1982
CNTR
1  WILLMANN 1999 quote both probability $\mathit P_{{{\mathit M}} {{\overline{\mathit M}}}}<8.3 \times 10^{-11}$ at 90$\%$CL in a $0.1~$T field and $\mathit R_{\mathit g}$= $\mathit G_{\mathit C}/\mathit G_{\mathit F}$.
2  GORDEEV 1997 quote limits on both $\mathit f=\mathit G_{{{\mathit M}} {{\mathit M}}}/\mathit GF$ and the probability $\mathit W_{{{\mathit M}} {{\mathit M}}}<4.7 \times 10^{-7}$ (90$\%$ CL).
3  ABELA 1996 quote both probability $\mathit P_{{{\mathit M}} {{\overline{\mathit M}}}}$ $<8 \times 10^{-9}$ at 90$\%$ CL and $\mathit R_{\mathit g}$ = $\mathit G_{\mathit C}/\mathit G_{\mathit F}$.
Conservation Laws:
LEPTON FAMILY NUMBER
References