1999/09/29 by The OPAL Collaboration, G. Abbiendi · 2 citations
Computer Science · Physics and Astronomy · #Computational Physics and Python Applications #Particle Detector Development and Performance #Particle physics theoretical and experimental studies #hep-ex
paper · pdf · doi:10.1007/s100520050733
published as Eur.Phys.J.C14:51-71,2000 · 41 pages, 16 figures, submitted to Eur Phys J C
arxiv created 1999/09/29 · openalex publication_date 2000/01/01 · arxiv updated 2009/11/30 · openalex created_date 2017/05/26 · openalex updated_date 2026/08/04
A selection of di-lepton events with significant missing transverse momentum has been performed using a total data sample of 237.4 pb-1 at e+e- centre-of-mass energies of 183 GeV and 189 GeV. The observed numbers of events - 78 at 183 GeV and 301 at 189 GeV - are consistent with the numbers expected from Standard Model processes, which arise predominantly from W+W- production with each W decaying leptonically. This topology is also an experimental signature for the pair production of new particles that decay to a charged lepton accompanied by one or more invisible particles. Discrimination techniques are described that optimise the sensitivity to particular new physics channels. No evidence for new phenomena is apparent and model independent limits are presented on the production cross-section times branching ratio squared for sleptons and for leptonically decaying charginos and charged Higgs. Assuming a 100 % branching ratio for the decay of a slepton to a lepton and the lightest neutralino, we exclude at 95 % CL: right-handed smuons with masses below 82.3 GeV for a smuon-neutralino mass difference > 3 Gev and right-handed staus with masses below 81.0 GeV for a stau-neutralino mass difference > 8 GeV. Right-handed selectrons are excluded at 95% CL for masses below 87.1 GeV for a selectron-neutralino mass diffeerence > 5GeV, within the framework of the Minimal Supersymmetric Standard Model assuming mu < -100 GeV and tanbeta = 1.5. Charged Higgs bosons are excluded at 95% CL for masses below 82.8GeV, assuming a 100% branching ratio for their decay to tau+neutrino.