Browsing by Author " Abicht, N.J."

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    Improved reconstruction of highly boosted τ -lepton pairs in the τ τ → ( μ ν μ ν τ ) ( hadrons + ν τ ) decay channels with the ATLAS detector
    (2025) Aad, G.; Aakvaag, E. ; Abbott, B. ; Abdelhameed, S.; Abeling, K. ; Abicht, N.J.; Abidi, S.H.; Aboelela, M.; Aboulhorma, A.; Abramowicz, H.; Abulaiti, Y.; Acharya, B.S. ; Ackermann, A.; Adam Bourdarios, C.; Adamczyk, L. ; Addepalli, S. V.; Addison, M. J. ; Díaz, Marco A.; Garay Walls, F.M.; Urrejola, P.; ATLAS Collaboration
    This paper presents a new τ -lepton reconstruction and identification procedure at the ATLAS detector at the Large Hadron Collider, which leads to significantly improved performance in the case of physics processes where a highly boosted pair of τ -leptons is produced and one τ -lepton decays into a muon and two neutrinos ( τ μ ), and the other decays into hadrons and one neutrino ( τ had ). By removing the muon information from the signals used for reconstruction and identification of the τ had candidate in the boosted pair, the efficiency is raised to the level expected for an isolated τ had . The new procedure is validated by selecting a sample of highly boosted Z → τ μ τ had candidates from the data sample of 140  fb - 1 of proton–proton collisions at 13 TeV recorded with the ATLAS detector. Good agreement is found between data and simulation predictions in both the Z → τ μ τ had signal region and in a background validation region. The results presented in this paper demonstrate the effectiveness of the τ had reconstruction with muon removal in enhancing the signal sensitivity of the boosted τ μ τ had channel at the ATLAS detector.
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    Measurement and interpretation of same-sign W boson pair production in association with two jets in pp collisions at √s = 13 TeV with the ATLAS detector
    (2024) Aad G.; Abbott, B.; Abeling, K.; Abicht, N.J.; Abidi, S.H.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Abusleme Hoffman, Ángel Christian; Acharya, B. S.; Bourdarios, C. Adam; Adamczyk, L.; Adamek, L.; Addepalli, S. V.; Addison, M.J.; Adelman, J.; Díaz, Marco A.; Garay Walls, Francisca; ATLAS Collaboration
    This paper presents the measurement of fducial and diferential cross sections for both the inclusive and electroweak production of a same-sign W-boson pair in association with two jets (W±W±jj) using 139 fb−1 of proton-proton collision data recorded at a centre-of-mass energy of √s = 13 TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed by selecting two same-charge leptons, electron or muon, and at least two jets with large invariant mass and a large rapidity diference. The measured fducial cross sections for electroweak and inclusive W±W±jj production are 2.92 ± 0.22 (stat.) ± 0.19 (syst.)fb and 3.38±0.22 (stat.)±0.19 (syst.)fb, respectively, in agreement with Standard Model predictions. The measurements are used to constrain anomalous quartic gauge couplings by extracting 95% confdence level intervals on dimension-8 operators. A search for doubly charged Higgs bosons H±± that are produced in vector-boson fusion processes and decay into a same-sign W boson pair is performed. The largest deviation from the Standard Model occurs for an H±± mass near 450 GeV, with a global signifcance of 2.5 standard deviations.