DELPHI LEP172 EVENTS, RADIATIVE RETURN
DELPHI Events from the 172 GeV Run
Events from radiative return
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e+ e- --> e+ e- gamma
e+ e- --> mu+ mu- gamma
e+ e- --> tau+ tau- gamma
e+ e- --> q qbar gamma
e+ e- --> 2 gamma, acoplanar
- The following two events were selected in the search for the reaction
e+ e- -->
Chi01 Chi01 ,
with Chi01 --> gamma + gravitino
for which the signature consists in two gammas with large missing momentum
and which are not coplanar with the beam.
- r070972e008114, 2 acoplanar gammas
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This event has one photon detected in the HPC, the other in the EMF.
The HPC photon has 35.6 GeV and the EMF photon has 30.0 GeV.
The acoplanarity is of 161 degree, the missing momentum is 42.5 GeV/c.
The recoiling system has 98.2 GeV mass, not far from the Z0.
The most likely interpretation is as a
Z0 gamma gamma final state with the Z0 decaying into a
neutrino pair.
This event was presented by:
Daniel Treille at the FRC of 6/11/96.
Jan Timmermans at the LEPC of 19/11/96.
- r070972e008114, 2 acoplanar gammas
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In this event, both photons are detected in the HPC, one with 27 GeV,
the other with 13.3 GeV.
The acoplanarity is of 116 degree, the missing momentum is 34.5 GeV/c.
The recoiling system has 127.5 GeV mass, significantly above the Z0.
The most likely interpretation is nevertheless as a
neutrino anti-neutrino 3gamma final state where one gamma
escaped in the beam pipe.
Simulation shows that, when one gamma is missed, the recoil mass distribution
develops a tail which is at about 10% of the Z0 peak.
This event was presented by:
Daniel Treille at the FRC of 6/11/96.
Jan Timmermans at the LEPC of 19/11/96.