DELPHI LEP183 EVENTS, WW+ZZ CAND
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D E L P H I |
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Events from 183 GeV |
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W+W- or ZZ Candidates |
Below is a sample of events taken by the DELPHI experiment during
the period where the LEP accelerator was running at 183 GeV energy in 1997.
To get the full size picture of an event (in Postscript), click on the icon.
To get its description, click on the label below the icon.
W+W- Events :
e+ e- --> W+ W- :
- r080931e010721,
(Mu Nu) + (q qbar) decay
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zy shaded view
| energy flow
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The event has a clear muon (green), MIP in the Barrel Hadron Calorimeter and
with hits associated (in red) in the Barrel Muon Chambers.
In addition, there is a two-jet structure with mass of about 77 GeV,
compatible with being a W.
The recoil mass to the jets is 81 GeV.
The jet structure is also clearly visible in the energy flow plot (colors
are the same as for the left figure).
Z0Z0 Events :
e+ e- --> Z0 Z0 :
- r075817e002704,
(Mu Mu) + (q qbar) decay
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xy shaded view
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Candidate Z0Z0 event, where one Z decays into a Mu-Mu (in yellow) and the
other into a quark-antiquark pair
(pictures prepared by Morgan Lethuillier).
The muon pair is not collinear, showing that the Z0 is off-shell.
For the quark pair,
b-tagging gives no evidence that the quark flavours would be beauty.
- r078214e000478,
(Mu Mu) + (q qbar) decay
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xy shaded view
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Candidate Z0Z0 event, where one Z decays into a Mu-Mu (in yellow) and the
other into a quark-antiquark pair
(pictures prepared by Morgan Lethuillier).
The muon pair has a reconstructed mass of approximately 88 GeV.
The quark pair has a mass of about 86 GeV.
The b-tagging gives evidence that the quark flavours are beauty.
This event was selected in the search for hZ,
but is compatible with being a ZZ, one of the Z0s decaying into b quarks.
- r080795e001374,
(Mu Mu) + (q qbar) decay
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xy view
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Candidate Z0Z0 event, where one Z produces a Mu-Mu (in red) and the
other a quark-antiquark pair.
The Mu+ is accompanied by a 17 GeV shower in the HPC.
If the Mu-Mu effective mass is computed without the shower, it is about 70 GeV.
With the shower included, it is 89 GeV, hence
the shower in the HPC is due to final state radiation in the
decay of the Z0.
Both final state jets are b-tagged.
Several kinematical fits were attempted, all leading to a Mu-Mu-gam mass of
89.0 GeV and a recoil mass of 90.7 GeV.
The event was selected as a hZ candidate,
but is also compatible with Z0Z0 production,
one of them decaying into b quarks.