Examinando por Autor "Abed Abud A."

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    Measurement of the tt¯ production cross-section in the lepton+jets channel at s=13 TeV with the ATLAS experiment
    (Elsevier B.V., 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.
    The top anti-top quark production cross-section is measured in the lepton+jets channel using proton–proton collision data at a centre-of-mass energy of s=13 TeV collected with the ATLAS detector at the LHC. The dataset corresponds to an integrated luminosity of 139 fb−1. Events with exactly one charged lepton and four or more jets in the final state, with at least one jet containing b-hadrons, are used to determine the tt¯ production cross-section through a profile-likelihood fit. The inclusive cross-section is measured to be σinc=830±0.4(stat.)±36(syst.)±14(lumi.)pb with a relative uncertainty of 4.6%. The result is consistent with theoretical calculations at next-to-next-to-leading order in perturbative QCD. The fiducial tt¯ cross-section within the experimental acceptance is also measured. © 2020 The Author(s)
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    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.
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    Reconstruction and identification of boosted di-τ systems in a search for Higgs boson pairs using 13 TeV proton-proton collision data in ATLAS
    (Springer Science and Business Media Deutschland GmbH, 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. [et al]
    In this paper, a new technique for reconstructing and identifying hadronically decaying τ+τ− pairs with a large Lorentz boost, referred to as the di-τ tagger, is developed and used for the first time in the ATLAS experiment at the Large Hadron Collider. A benchmark di-τ tagging selection is employed in the search for resonant Higgs boson pair production, where one Higgs boson decays into a boosted bb¯ pair and the other into a boosted τ+τ− pair, with two hadronically decaying τ-leptons in the final state. Using 139 fb−1 of proton-proton collision data recorded at a centre-of-mass energy of 13 TeV, the efficiency of the di-τ tagger is determined and the background with quark- or gluon-initiated jets misidentified as di-τ objects is estimated. The search for a heavy, narrow, scalar resonance produced via gluon-gluon fusion and decaying into two Higgs bosons is carried out in the mass range 1–3 TeV using the same dataset. No deviations from the Standard Model predictions are observed, and 95% confidence-level exclusion limits are set on this model. [Figure not available: see fulltext.]. © 2020, The Author(s).
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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. .
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    Search for Higgs boson production in association with a high-energy photon via vector-boson fusion with decay into bottom quark pairs at √s = 13 TeV with the ATLAS detector
    (Springer Science and Business Media Deutschland GmbH, 2021-03) 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 is presented for the production of the Standard Model Higgs boson in association with a high-energy photon. With a focus on the vector-boson fusion process and the dominant Higgs boson decay into b-quark pairs, the search benefits from a large reduction of multijet background compared to more inclusive searches. Results are reported from the analysis of 132 fb−1 of pp collision data at s = 13 TeV collected with the ATLAS detector at the LHC. The measured Higgs boson signal yield in this final-state signature is 1.3 ± 1.0 times the Standard Model prediction. The observed significance of the Higgs boson signal above the background is 1.3 standard deviations, compared to an expected significance of 1.0 standard deviations. [Figure not available: see fulltext.] © 2021, The Author(s).
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    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.