Search for Anomalous Photonic Events with Missing Energy in e+e- Collisions at Ecm = 130, 136 and 183 GeV

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dc.creatorThe OPAL Collaboration
dc.creatoral, G. Abbiendi et
dc.date1998-10-09
dc.date.accessioned2026-07-07T12:02:26Z
dc.date.available2026-07-07T12:02:26Z
dc.descriptionPhotonic events with large missing energy have been observed in e+e- collisions at centre-of-mass energies of 130, 136 and 183 GeV collected in 1997 using the OPAL detector at LEP. Results are presented for event topologies with a single photon and missing transverse energy or with an acoplanar photon pair. Cross-section measurements are performed within the kinematic acceptance of each selection. These results are compared with the expectations from the Standard Model process e+e- to nunubar + photon(s). No evidence is observed for new physics contributions to these final states. Using the data at Ecm = 183 GeV, upper limits on sigma(e+e- to X.Y)*BR(X to Y gamma) and sigma(e+e- to X.X)*BR(X to Y gamma)**2 are derived for the case of stable and invisible Y. These limits apply to single and pair production of excited neutrinos (X = nu*, Y = nu), to neutralino production (X = Chi_2^0, Y = Chi_1^0) and to supersymmetric models in which X = chi_1^0 and Y is a light gravitino.
dc.description36 pages, LaTeX, including 15 ps figures, submitted to European Physical Journal C
dc.identifierhttps://arxiv.org/abs/hep-ex/9810021
dc.identifierhttp://arxiv.org/abs/hep-ex/9810021
dc.identifierEur.Phys.J.C8:23-40,1999
dc.identifierdoi:10.1007/s100520050442
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/207440
dc.subjectHigh Energy Physics - Experiment
dc.titleSearch for Anomalous Photonic Events with Missing Energy in e+e- Collisions at Ecm = 130, 136 and 183 GeV
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