ATLAS

Abstract:

We report on a search for the flavor-changing neutral current decays B⁰ d, s→μ⁺μ⁻, B⁺→μ⁺μ⁻K⁺, and B⁰→μ⁺μ⁻K^*0 using data from pp^- collisions at s = 1.8 TeV, collected with the Collider Detector at Fermilab during the 1992-1993 running period. We find no indication of such decays, and we set the following 90% confidence level upper limits on branching ratios: B\(B⁰→μ⁺μ⁻\)<1.6×10⁻⁶, B(B⁰ s→μ⁺μ⁻\)<8.4×10⁻⁶, B\(B⁺→μ⁺μ⁻K⁺\)<1.0×10⁻⁵, and B\(B⁰→μ⁺μ⁻K^*0\)<2.5×10⁻⁵. © 1996 The American Physical Society.

Abstract:

We present results from a search for anomalous WW and WZ production in pp^¯ collisions at √s = 1.8 TeV. We used pp^¯ → evjjX events observed during the 1992-1993 run of the Fermilab Tevatron collider, corresponding to an integrated luminosity of 13.7 ± 0.7pb⁻¹. A fit to the transverse momentum spectrum of the W boson yields direct limits on the CP-conserving anomalous WWγ and WWZ coupling parameters of −0.9 < Δk < 1.1 (with λ = 0) and −0.6 < λ < 0.7 (with Δk = 0) at the 95% confidence level, for a form factor scale Λ = 1.5 TeV, assuming that the WWγ and WWZ coupling parameters are equal. © 1996 The American Physical Society.

Abstract:

We present the result of a search for charged Higgs boson decays of the top quark, produced in p-p collisions at √s=1.8 TeV. When the charged Higgs boson is heavy and decays to a τ lepton, which subsequently decays hadronically, the resulting events have a unique signature: large missing transverse energy and the low-charged-multiplicity τ. Data collected in 1992 and 1993 at the Collider Detector at Fermilab, corresponding to 18.7±0.7 pb^-1, exclude new regions of combined top quark and charged Higgs boson mass, in extensions to the standard model with two Higgs doublets. © 1996 The American Physical Society.

Abstract:

We have searched for chargino-neutralino production (χ^± 1χ⁰ 2) in 1.8 TeV pp collisions, followed by their leptonic decays χ^± 1 → χ⁰ 1ℓ^±ν and χ⁰ 2→χ⁰ 1ℓ⁺ℓ^-. These trilepton events are expected within a framework of the minimal supersymmetric standard model (MSSM). In a 19.1pb^-1 data sample collected with a Collider Detector at Fermilab, no trilepton events were observed. Upper limits on σ(pp → χ^± 1χ⁰ 2)BR(χ^± 1→⁰ 2→3ℓ + X) were obtained for various MSSM parameter space regions, yielding new 95% confidence level lower limits for the neutralino (χ⁰ 2) mass which extend as high as 49GeV/c². © 1996 The American Physical Society.

Abstract:

We report on a search for supersymmetry using dilepton events which complements the classic missing ET plus multijet analyses. Using 19pb^-1 of pp collisions at √s = 1.8TeV recorded with the Collider Detector at Fermilab we have searched for squarks and gluinos decaying into charginos and producing events with two leptons. We observe one candidate event. In comparison, the expected number of background events from standard model processes is 2.39±0.63(stat)^+0.77 -0.42(syst). Hence we set limits on gluino and squark production based on predictions from the supergravity inspired minimal supersymmetric extension of the standard model. © 1996 The American Physical Society.