Examinando por Autor "Abouzeid O.S."

Mostrando 1 - 5 de 5
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    Ítem
    Observation and Measurement of Forward Proton Scattering in Association with Lepton Pairs Produced via the Photon Fusion Mechanism at ATLAS
    (American Physical Society, 2020-12) Aad G.; Abbott B.; Abbott D.C.; Abed Abud A.; Abeling K.; Abhayasinghe D.K.; Abidi S.H.; Abouzeid O.S.; Abraham N.L.; Abramowicz H.; Abreu H.; Abulaiti Y.; Acharya B.S.
    The observation of forward proton scattering in association with lepton pairs (e+e-+p or μ+μ-+p) produced via photon fusion is presented. The scattered proton is detected by the ATLAS Forward Proton spectrometer, while the leptons are reconstructed by the central ATLAS detector. Proton-proton collision data recorded in 2017 at a center-of-mass energy of s=13 TeV are analyzed, corresponding to an integrated luminosity of 14.6 fb-1. A total of 57 (123) candidates in the ee+p (μμ+p) final state are selected, allowing the background-only hypothesis to be rejected with a significance exceeding 5 standard deviations in each channel. Proton-tagging techniques are introduced for cross-section measurements in the fiducial detector acceptance, corresponding to σee+p=11.0±2.6(stat)±1.2(syst)±0.3(lumi) and σμμ+p=7.2±1.6(stat)±0.9(syst)±0.2(lumi) fb in the dielectron and dimuon channel, respectively. © 2020 CERN.
  • Miniatura
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    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in ffiffi s p = 13 TeV pp collisions with the ATLAS detector
    (American Physical Society, 2020-04) Aad G; Abbott B.; Abbott D.C; Abed Abud A; Abeling K; Abhayasinghe D.K.; Abidi S.H; Abouzeid O.S.; Abraham N.L; Abramowicz H.
    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of s=13 TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb-1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015-2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV. © 2020 CERN. © 2020 CERN, for the ATLAS Collaboration.
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    Search for Heavy Resonances Decaying into a Photon and a Hadronically Decaying Higgs Boson in pp Collisions at s =13 TeV with the ATLAS Detector
    (American Physical Society, 2020-12) Aad G.; Abbott B.; Abbott D.C.; Abed Abud A.; Abeling K.; Abhayasinghe D.K.; Abidi S.H.; Abouzeid O.S.; Abraham N.L.; Abramowicz H.; Abreu H.; Abulaiti Y.
    This Letter presents a search for the production of new heavy resonances decaying into a Higgs boson and a photon using proton-proton collision data at s=13 TeV collected by the ATLAS detector at the LHC. The data correspond to an integrated luminosity of 139 fb-1. The analysis is performed by reconstructing hadronically decaying Higgs boson (H→bb¯) candidates as single large-radius jets. A novel algorithm using information about the jet constituents in the center-of-mass frame of the jet is implemented to identify the two b quarks in the single jet. No significant excess of events is observed above the expected background. Upper limits are set on the production cross-section times branching fraction for narrow spin-1 resonances decaying into a Higgs boson and a photon in the resonance mass range from 0.7 to 4 TeV, cross-section times branching fractions are excluded between 11.6 fb and 0.11 fb at a 95% confidence level. © 2020 CERN.
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    Search for Higgs Boson Decays into a Z Boson and a Light Hadronically Decaying Resonance Using 13 TeV pp Collision Data from the ATLAS Detector
    (American Physical Society, 2020-11) Aad G.; Abbott B.; Abbott D.C.; Abed Abud A.; Abeling K.; Abhayasinghe D.K.; Abidi S.H.; Abouzeid O.S.; Abraham N.L.; Abramowicz H.; Abreu H.; Abulaiti Y.
    A search for Higgs boson decays into a Z boson and a light resonance in two-lepton plus jet events is performed, using a pp collision dataset with an integrated luminosity of 139 fb-1 collected at s=13 TeV by the ATLAS experiment at the CERN LHC. The resonance considered is a light boson with a mass below 4 GeV from a possible extended scalar sector or a charmonium state. Multivariate discriminants are used for the event selection and for evaluating the mass of the light resonance. No excess of events above the expected background is found. Observed (expected) 95% confidence-level upper limits are set on the Higgs boson production cross section times branching fraction to a Z boson and the signal resonance, with values in the range 17-340 pb (16-5+6-320-90+130 pb) for the different light spin-0 boson mass and branching fraction hypotheses, and with values of 110 and 100 pb (100-30+40 and 100-30+40 pb) for the ηc and J/ψ hypotheses, respectively. .
  • Miniatura
    Ítem
    Search for resonances decaying into a weak vector boson and a Higgs boson in the fully hadronic final state produced in proton-proton collisions at s =13 TeV with the ATLAS detector
    (American Physical Society, 2020-12) Aad G.; Abbott D.C.; Abed Abud A.; Abeling K.; Abhayasinghe D.K.; Abidi S.H.; Abouzeid O.S.; Abraham N.L.; Abramowicz H.; Abreu H.; Abulaiti Y.
    A search for heavy resonances decaying into a W or Z boson and a Higgs boson produced in proton-proton collisions at the Large Hadron Collider at s=13 TeV is presented. The analysis utilizes the dominant W→qq¯′ or Z→qq¯ and H→bb¯ decays with substructure techniques applied to large-radius jets. A sample corresponding to an integrated luminosity of 139 fb-1 collected with the ATLAS detector is analyzed and no significant excess of data is observed over the background prediction. The results are interpreted in the context of the heavy vector triplet model with spin-1 W′ and Z′ bosons. Upper limits on the cross section are set for resonances with mass between 1.5 and 5.0 TeV, ranging from 6.8 to 0.53 fb for W′→WH and from 8.7 to 0.53 fb for Z′→ZH at the 95% confidence level. © 2020 CERN.