${{\mathit A}^{0}}$ (Axion) Searches in Positronium Decays

INSPIRE   PDGID:
S029AXD
Decay or transition of positronium. Limits are for branching ratio.
VALUE CL% DOCUMENT ID TECN  COMMENT
• • We do not use the following data for averages, fits, limits, etc. • •
$<4.4 \times 10^{-5}$ 90 1
BADERTSCHER
2002
CNTR $\mathit o$-Ps $\rightarrow$ ${{\mathit \gamma}}{{\mathit X}_{{{1}}}}{{\mathit X}_{{{2}}}}$, ${\mathit m}_{{{\mathit X}_{{{1}}}}}+{\mathit m}_{{{\mathit X}_{{{2}}}}}{}\leq{}$900 keV
$<2 \times 10^{-4}$ 90
MAENO
1995
CNTR $\mathit o$-Ps $\rightarrow$ ${{\mathit A}^{0}}{{\mathit \gamma}}{\mathit m}_{{{\mathit A}^{0}}}=850 - 1013$ keV
$<3.0 \times 10^{-4}$ 90 2
ASAI
1994
CNTR $\mathit o$-Ps $\rightarrow$ ${{\mathit A}^{0}}{{\mathit \gamma}}{\mathit m}_{{{\mathit A}^{0}}}=30 - 500$ keV
$<2.8 \times 10^{-5}$ 90 3
AKOPYAN
1991
CNTR $\mathit o$-Ps $\rightarrow$ ${{\mathit A}^{0}}{{\mathit \gamma}}$ ( ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$), ${\mathit m}_{{{\mathit A}^{0}}}$ $<$ 30 keV
$<1.1 \times 10^{-6}$ 90 4
ASAI
1991
CNTR $\mathit o$-Ps $\rightarrow$ ${{\mathit A}^{0}}{{\mathit \gamma}}$, ${\mathit m}_{{{\mathit A}^{0}}}$ $<$ 800 keV
$<3.8 \times 10^{-4}$ 90
GNINENKO
1990
CNTR $\mathit o$-Ps $\rightarrow$ ${{\mathit A}^{0}}{{\mathit \gamma}}$, ${\mathit m}_{{{\mathit A}^{0}}}$ $<$ 30 keV
$<(1 - 5){\times }\text{ 10}$$^{-4}$ 95 5
TSUCHIAKI
1990
CNTR $\mathit o$-Ps $\rightarrow$ ${{\mathit A}^{0}}{{\mathit \gamma}}$, ${\mathit m}_{{{\mathit A}^{0}}}$ = $300-900$ keV
$<6.4 \times 10^{-5}$ 90 6
ORITO
1989
CNTR $\mathit o$-Ps $\rightarrow$ ${{\mathit A}^{0}}{{\mathit \gamma}}$, ${\mathit m}_{{{\mathit A}^{0}}}$ $<$ 30 keV
7
AMALDI
1985
CNTR Ortho-positronium
8
CARBONI
1983
CNTR Ortho-positronium
1  BADERTSCHER 2002 looked for a three-body decay of ortho-positronium into a photon and two penetrating (neutral or milli-charged) particles.
2  The ASAI 1994 limit is based on inclusive photon spectrum and is independent of ${{\mathit A}^{0}}$ decay modes.
3  The AKOPYAN 1991 limit applies for a short-lived ${{\mathit A}^{0}}$ with ${\mathit \tau}_{{{\mathit A}^{0}}}$ $<10^{-13}{\mathit m}_{{{\mathit A}^{0}}}$ [keV]$~$s.
4  ASAI 1991 limit translates to $\mathit g{}^{2}_{{{\mathit A}^{0}} {{\mathit e}^{+}} {{\mathit e}^{-}}}/4\pi $ $<$ $1.1 \times 10^{-11}$ (90$\%$ CL) for ${\mathit m}_{{{\mathit A}^{0}}}$ $<$ 800 keV.
5  The TSUCHIAKI 1990 limit is based on inclusive photon spectrum and is independent of ${{\mathit A}^{0}}$ decay modes.
6  ORITO 1989 limit translates to $\mathit g{}^{2}_{{{\mathit A}^{0}} {{\mathit e}} {{\mathit e}}}/4\pi $ $<$ $6.2 \times 10^{-10}$. Somewhat more sensitive limits are obtained for larger ${\mathit m}_{{{\mathit A}^{0}}}$: $\mathit B$ $<$ $7.6 \times 10^{-6}$ at 100 keV.
7  AMALDI 1985 set limits B(${{\mathit A}^{0}}{{\mathit \gamma}}$) $/$ B(${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \gamma}}$) $<$ (1$-5){\times }10^{-6}$ for ${\mathit m}_{{{\mathit A}^{0}}}$ = 900$-$100 keV which are about 1/10 of the CARBONI 1983 limits.
8  CARBONI 1983 looked for orthopositronium $\rightarrow$ ${{\mathit A}^{0}}{{\mathit \gamma}}$. Set limit for ${{\mathit A}^{0}}$ electron coupling squared, $\mathit g({{\mathit e}}{{\mathit e}}{{\mathit A}^{0}}){}^{2}/(4{}{{\mathit \pi}}$) $<6. \times 10^{-10}-7. \times 10^{-9}$ for ${\mathit m}_{{{\mathit A}^{0}}}$ from 150$-$900 keV (CL = $99.7\%$). This is about 1/10 of the bound from $\mathit g−$2 experiments.
References