3 research outputs found

    Search for R-parity-violating supersymmetry in a final state containing leptons and many jets with the ATLAS experiment using s√=13 TeV proton–proton collision data

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    A search for R-parity-violating supersymmetry in final states characterized by high jet multiplicity, at least one isolated light lepton and either zero or at least three b-tagged jets is presented. The search uses 139fb−1 of s√=13 TeV proton–proton collision data collected by the ATLAS experiment during Run 2 of the Large Hadron Collider. The results are interpreted in the context of R-parity-violating supersymmetry models that feature gluino production, top-squark production, or electroweakino production. The dominant sources of background are estimated using a data-driven model, based on observables at medium jet multiplicity, to predict the b-tagged jet multiplicity distribution at the higher jet multiplicities used in the search. Machine-learning techniques are used to reach sensitivity to electroweakino production, extending the data-driven background estimation to the shape of the machine-learning discriminant. No significant excess over the Standard Model expectation is observed and exclusion limits at the 95% confidence level are extracted, reaching as high as 2.4 TeV in gluino mass, 1.35 TeV in top-squark mass, and 320 (365) GeV in higgsino (wino) mass

    Luminosity Determination in pp Collisions at 1a(s)=7 TeV Using the ATLAS Detector at the LHC

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    Search for promptly produced heavy quarkonium states in hadronic Z decays

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    A search has been made for direct production of heavy quarkonium states in more than 3 million hadronic Z(0) decays in the 1991-1994 DELPHI data, Prompt J/psi, psi(2S) and Upsilon candidates have been searched for through their leptonic decay modes using criteria based on the kinematics and decay vertex positions. New upper limits are set at the 90% confidence level for Br(Z(0) –> (Q (Q) over bar) X)/Br(Z(0) –> hadrons) for various strong production mechanisms of J/psi and Upsilon; these range down to 0.9 x 10(-4). The limits are set in the presence of a small excess (similar to 1% statistical probability of a background fluctuation) in the sum of candidates from prompt J/psi, psi(2S), Upsilon(1S), Upsilon(2S) and Upsilon(3S) relative to the estimated background
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