MASS LIMITS for a Heavy Neutral Boson Coupling to ${{\mathit e}^{+}}{{\mathit e}^{-}}$

INSPIRE   JSON  (beta) PDGID:
S056HEE
VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT
• • We do not use the following data for averages, fits, limits, etc. • •
$\text{none 55-61}$ 1
ODAKA
1989
VNS $\Gamma\mathrm {({{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}})}$ $\cdot{}$ B(${{\mathit X}^{0}}$ $\rightarrow$ had.)${ {}\gtrsim{} }$0.2 MeV
$>45$ 95 2
DERRICK
1986
HRS $\Gamma\mathrm {({{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}})}$=6 MeV
$>46.6$ 95 3
ADEVA
1985
MRKJ $\Gamma\mathrm {({{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}})}$=10 keV
$>48$ 95 3
ADEVA
1985
MRKJ $\Gamma\mathrm {({{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}})}$=4 MeV
4
BERGER
1985B
 PLUT
$\text{none 39.8 - 45.5}$ 5
ADEVA
1984
MRKJ $\Gamma\mathrm {({{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}})}$=10 keV
$>47.8$ 95 5
ADEVA
1984
MRKJ $\Gamma\mathrm {({{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}})}$=4 MeV
$\text{none 39.8 - 45.2}$ 5
BEHREND
1984C
 CELL
$>47$ 95 5
BEHREND
1984C
 CELL $\Gamma\mathrm {({{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}})}$=4 MeV
1  ODAKA 1989 looked for a narrow or wide scalar resonance in ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ hadrons at $\mathit E_{{\mathrm {cm}}}$ = $55.0-60.8$ GeV.
2  DERRICK 1986 found no deviation from the Standard Model Bhabha scattering at $\mathit E_{{\mathrm {cm}}}$= 29 GeV and set limits on the possible scalar boson ${{\mathit e}^{+}}{{\mathit e}^{-}}$ coupling. See their figure 4 for excluded region in the $\Gamma\mathrm {({{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}})}-{\mathit m}_{{{\mathit X}^{0}}}$ plane. Electronic chiral invariance requires a parity doublet of ${{\mathit X}^{0}}$, in which case the limit applies for $\Gamma\mathrm {({{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}})}$ = 3 MeV.
3  ADEVA 1985 first limit is from 2${{\mathit \gamma}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$, hadrons assuming ${{\mathit X}^{0}}$ is a scalar. Second limit is from ${{\mathit e}^{+}}{{\mathit e}^{-}}$ channel. $\mathit E_{{\mathrm {cm}}}$ = 40$-$47 GeV. Supersedes ADEVA 1984.
4  BERGER 1985B looked for effect of spin-0 boson exchange in ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ and ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ at $\mathit E_{{\mathrm {cm}}}$ = $34.7$ GeV. See Fig.$~$5 for excluded region in the ${\mathit m}_{{{\mathit X}^{0}}}−\Gamma\mathrm {({{\mathit X}^{0}})}$ plane.
5  ADEVA 1984 and BEHREND 1984C have $\mathit E_{{\mathrm {cm}}}$ = 39.8$-$45.5 GeV. MARK-J searched ${{\mathit X}^{0}}$ in ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ hadrons, 2${{\mathit \gamma}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$, ${{\mathit e}^{+}}{{\mathit e}^{-}}$ and CELLO in the same channels plus ${{\mathit \tau}}$ pair. No narrow or broad ${{\mathit X}^{0}}$ is found in the energy range. They also searched for the effect of ${{\mathit X}^{0}}$ with ${\mathit m}_{{{\mathit X}}}$ $>\mathit E_{{\mathrm {cm}}}$. The second limits are from Bhabha data and for spin-0 singlet. The same limits apply for $\Gamma\mathrm {({{\mathit X}^{0}} \rightarrow {{\mathit e}^{+}} {{\mathit e}^{-}})}$ = 2 MeV if ${{\mathit X}^{0}}$ is a spin-0 doublet. The second limit of BEHREND 1984C was read off from their figure 2. The original papers also list limits in other channels.
References