Multi-photon production in e+e- collisions at sqrt(s)= 189 geV

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dc.creatorThe OPAL collaboration
dc.creatorAbbiendi, G.
dc.date1999-07-30
dc.date.accessioned2026-07-07T12:02:34Z
dc.date.available2026-07-07T12:02:34Z
dc.descriptionThe process e+e- to 2 (or 3) gammas is studied using data recorded with the OPAL detector at LEP. The data sample taken at a centre-of-mass energy of 189 GeV corresponds to a total integrated luminosity of 178 pb-1. The measured cross-section agrees well with the expectation from QED. A fit to the angular distribution is used to obtain improved limits at 95% CL on the QED cut-off parameters: Lambda+ > 304 GeV and Lambda- > 295 GeV as well as a mass limit for an excited electron, Me* > 306 GeV assuming equal e*egamma and eegamma couplings. Graviton exchange in the context of theories with higher dimensions is excluded for scales G+ < 660 GeV and G- < 634 GeV. No evidence for resonance production is found in the invariant mass spectrum of photon pairs. Limits are obtained for the cross-section times branching ratio for a resonance decaying into two photons and produced in association with another photon.
dc.description22 pages, 7 figures, submitted to Phys. Lett
dc.identifierhttps://arxiv.org/abs/hep-ex/9907064
dc.identifierhttp://arxiv.org/abs/hep-ex/9907064
dc.identifierPhys.Lett.B465:303-314,1999
dc.identifierdoi:10.1016/S0370-2693(99)01092-8
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/207481
dc.subjectHigh Energy Physics - Experiment
dc.titleMulti-photon production in e+e- collisions at sqrt(s)= 189 geV
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