Search for neutral heavy leptons produced in Z decays

Collaboration
Dec, 1996
27 pages
Published in:
  • Z.Phys.C 74 (1997) 57-71,
  • Z.Phys.C 75 (1997) 580 (erratum)
Report number:
  • CERN-PPE-96-195
Experiments:

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Abstract: (Springer)
Weak isosinglet Neutral Heavy Leptons (vm) have been searched for using data collected by the DELPHI detector corresponding to 3.3 × 106 hadronic Z0 decays at LEP1. Four separate searches have been performed, for short-lived vm production giving monojet or acollinear jet topologies, and for long-lived vm giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z0 → vm?) of about 1.3 × 10−6 at 95% confidence level for vm masses between 3.5 and 50 GeV/c2. Outside this range the limit weakens rapidly with the vm mass. The results are also interpreted in terms of limits for the single production of excited neutrinos.
  • electron positron: colliding beams
  • electron positron: annihilation
  • Z0: electroproduction
  • Z0: leptonic decay
  • heavy lepton: search for
  • neutrino: pair production
  • neutrino: massive
  • neutrino: decay
  • neutrino: excited state
  • neutrino: lifetime
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