Search for ${{\boldsymbol X}^{0}}$ (Light Boson) Resonance in ${{\boldsymbol e}^{+}}$ ${{\boldsymbol e}^{-}}$ $\rightarrow$ ${{\boldsymbol \gamma}}{{\boldsymbol \gamma}}{{\boldsymbol \gamma}}$ INSPIRE search

The limit is for $\Gamma\mathrm {( {{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}} )}\cdot{}\Gamma\mathrm {( {{\mathit X}^{0}} \rightarrow {{\mathit \gamma}} {{\mathit \gamma}} {{\mathit \gamma}} )}/\Gamma _{{\mathrm {total}}}$. $\mathit C$ invariance forbids spin-0 ${{\mathit X}^{0}}$ coupling to both ${{\mathit e}^{+}}{{\mathit e}^{-}}$ and ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \gamma}}$ .
VALUE ($10^{-3}$ eV) CL% DOCUMENT ID TECN  COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •
$<0.2$ 95 1
 1994
CNTR ${\mathit m}_{{{\mathit X}^{0}}}=1.1 - 1.9$ MeV
$<1.0$ 95 2
 1994
CNTR ${\mathit m}_{{{\mathit X}^{0}}}=1.1$ MeV
$<2.5$ 95 2
 1994
CNTR ${\mathit m}_{{{\mathit X}^{0}}}=1.4$ MeV
$<120$ 95 2
 1994
CNTR ${\mathit m}_{{{\mathit X}^{0}}}=1.7$ MeV
$<3.8$ 95 3
 1992
CNTR ${\mathit m}_{{{\mathit X}^{0}}}$= 1.5 MeV
1  VO 1994 looked for ${{\mathit X}^{0}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \gamma}}$ decaying at rest. The precise limits depend on ${\mathit m}_{{{\mathit X}^{0}}}$. See Fig.$~$2(b) in paper.
2  VO 1994 looked for ${{\mathit X}^{0}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}{{\mathit \gamma}}$ decaying in flight.
3  SKALSEY 1992 also give limits $4.3$ for ${\mathit m}_{{{\mathit X}^{0}}}$ = $1.54$ and $7.5$ for $1.64$ MeV. The spin of ${{\mathit X}^{0}}$ is assumed to be one.
References:
 VO 1994
PR C49 1551 Search for Resonance in Multiphoton Final States from Low Energy ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Scattering
 SKALSEY 1992
PRL 68 456 Search for Three Photon Final State Resonances in Low-Energy ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Scattering