Search for anomalous production of photonic events with missing energy in e+e- collisions at √s = 130-172 GeV

The OPAL Collaboration

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Photonic events with large missing energy have been observed in e+e- collisions at centre-of-mass energies of 130, 136, 161 and 172 GeV using the OPAL detector at LEP. Results are presented based on search topologies designed to select events with a single photon and missing transverse energy or events with a pair of acoplanar photons. In both search topologies, cross-section measurements are performed within the kinematic acceptance of the selection. These results are compared with the expectations from the Standard Model processes e+e- → vv̄γ(γ) (single-photon) and e+e- → vv̄γγ(γ) (acoplanar-photons). No evidence is observed for new physics contributions to these final states. Upper limits on σ(e+e- → XY) · BR(X → Yγ) and σ(e+e- → XX) · BR2(X → Yγ) are derived for the case of stable and invisible Y. These limits apply to single and pair production of excited neutrinos (X = v*, Y = v), to neutralino production (X = χ̃02, Y = χ̃01), and to supersymmetric models in which X = χ̃01 and Y = G̃ is a light gravitino. For the latter scenario, the results of the acoplanar-photons search are used to provide model-dependent lower limits on the mass of the lightest neutralino.

Original languageEnglish
Pages (from-to)607-625
Number of pages19
JournalEuropean Physical Journal C
Volume2
Issue number4
DOIs
StatePublished - 1 Jan 1998
Externally publishedYes

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Physics and Astronomy (miscellaneous)

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