Araştırma Çıktıları | WoS | Scopus | TR-Dizin | PubMed
Permanent URI for this communityhttps://hdl.handle.net/20.500.14719/1741
Browse
7 results
Search Results
Publication Open Access Top-quark mass measurement in the all-hadronic tt¯ decay channel at √s=8 TeV with the ATLAS detector(Springer Verlag [email protected], 2017) Aaboud, M.; Aad, Georges; Abbott, Brad K.; Abdallah, Jalal Mohamad; Abdinov, O. B.; Abeloos, Baptiste; Aben, R.; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; Aaboud, M., Université Mohammed Premier Oujda, Oujda, Morocco; Aad, Georges, Aix Marseille Université, Marseille, France; Abbott, Brad K., Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, Norman, United States; Abdallah, Jalal Mohamad, Department of Physics, The University of Texas at Arlington, Arlington, United States; Abdinov, O. B., Azerbaijan National Academy of Sciences, Baku, Azerbaijan; Abeloos, Baptiste, Laboratoire de l'Accélérateur Linéaire, Orsay, France; Aben, R., Universiteit van Amsterdam, Amsterdam, Netherlands; AbouZeid, O. S., Santa Cruz Institute for Particle Physics, Santa Cruz, United States; Abraham, Nicola L., Department of Physics and Astronomy, University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv-Yafo, IsraelThe top-quark mass is measured in the all-hadronic top-antitop quark decay channel using proton-proton collisions at a centre-of-mass energy of s=8 TeV with the ATLAS detector at the CERN Large Hadron Collider. The data set used in the analysis corresponds to an integrated luminosity of 20.2 fb −1 . The large multi-jet background is modelled using a data-driven method. The top-quark mass is obtained from template fits to the ratio of the three-jet to the dijet mass. The three-jet mass is obtained from the three jets assigned to the top quark decay. From these three jets the dijet mass is obtained using the two jets assigned to the W boson decay. The top-quark mass is measured to be 173.72 ± 0.55 (stat.) ± 1.01 (syst.) GeV.[Figure not available: see fulltext.]. © 2019 Elsevier B.V., All rights reserved.Publication Open Access Search for top quark decays t → qH, with H → γγ, in √s=13 TeV pp collisions using the ATLAS detector(Springer Verlag, 2017) Aaboud, M.; Aad, Georges; Abbott, Brad K.; Abdinov, O. B.; Abeloos, Baptiste; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; Abreu, Henso; Aaboud, M., Faculty of Science, Université Mohammed Premier Oujda, Oujda, Morocco; Aad, Georges, Centre de Physique des Particules de Marseille, Marseille, France; Abbott, Brad K., The University of Oklahoma, Norman, United States; Abdinov, O. B., Azerbaijan National Academy of Sciences, Baku, Azerbaijan; Abeloos, Baptiste, Laboratoire de l'Accélérateur Linéaire, Orsay, France; Abidi, Syed Hani, University of Toronto, Toronto, Canada; AbouZeid, O. S., Santa Cruz Institute for Particle Physics, Santa Cruz, United States; Abraham, Nicola L., University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Tel Aviv University, Tel Aviv-Yafo, Israel; Abreu, Henso, Department of Physics, Technion - Israel Institute of Technology, Haifa, IsraelThis article presents a search for flavour-changing neutral currents in the decay of a top quark into an up-type (q = c, u) quark and a Higgs boson, where the Higgs boson decays into two photons. The proton-proton collision data set analysed amounts to 36.1 fb−1 at s=13 TeV collected by the ATLAS experiment at the LHC. Top quark pair events are searched for, where one top quark decays into qH and the other decays into bW. Both the hadronic and leptonic decay modes of the W boson are used. No significant excess is observed and an upper limit is set on the t → cH branching ratio of 2.2 × 10−3 at the 95% confidence level, while the expected limit in the absence of signal is 1.6 × 10−3. The corresponding limit on the tcH coupling is 0.090 at the 95% confidence level. The observed upper limit on the t → uH branching ratio is 2.4 × 10−3.[Figure not available: see fulltext.]. © 2025 Elsevier B.V., All rights reserved.Publication Open Access Measurement of the tt¯ γ production cross section in proton-proton collisions at √s=8 TeV with the ATLAS detector(Springer Verlag, 2017) Aaboud, M.; Aad, Georges; Abbott, Brad K.; Abdinov, O. B.; Abeloos, Baptiste; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; Abreu, Henso; Aaboud, M., Faculty of Science, Université Mohammed Premier Oujda, Oujda, Morocco; Aad, Georges, Centre de Physique des Particules de Marseille, Marseille, France; Abbott, Brad K., The University of Oklahoma, Norman, United States; Abdinov, O. B., Azerbaijan National Academy of Sciences, Baku, Azerbaijan; Abeloos, Baptiste, Laboratoire de l'Accélérateur Linéaire, Orsay, France; Abidi, Syed Hani, University of Toronto, Toronto, Canada; AbouZeid, O. S., Santa Cruz Institute for Particle Physics, Santa Cruz, United States; Abraham, Nicola L., University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Tel Aviv University, Tel Aviv-Yafo, Israel; Abreu, Henso, Department of Physics, Technion - Israel Institute of Technology, Haifa, IsraelThe cross section of a top-quark pair produced in association with a photon is measured in proton-proton collisions at a centre-of-mass energy of s=8 TeV with 20.2 fb−1 of data collected by the ATLAS detector at the Large Hadron Collider in 2012. The measurement is performed by selecting events that contain a photon with transverse momentum pT > 15 GeV, an isolated lepton with large transverse momentum, large missing transverse momentum, and at least four jets, where at least one is identified as originating from a b-quark. The production cross section is measured in a fiducial region close to the selection requirements. It is found to be 139 ± 7 (stat.) ± 17 (syst.) fb, in good agreement with the theoretical prediction at next-to-leading order of 151 ± 24 fb. In addition, differential cross sections in the fiducial region are measured as a function of the transverse momentum and pseudorapidity of the photon.[Figure not available: see fulltext.]. © 2025 Elsevier B.V., All rights reserved.Publication Open Access Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the t-channel at √s=8 TeV with the ATLAS detector(Springer Verlag, 2017) Aaboud, M.; Aad, Georges; Abbott, Brad K.; Abdallah, Jalal Mohamad; Abdinov, O. B.; Abeloos, Baptiste; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; Aaboud, M., Faculty of Science, Université Mohammed Premier Oujda, Oujda, Morocco; Aad, Georges, Centre de Physique des Particules de Marseille, Marseille, France; Abbott, Brad K., The University of Oklahoma, Norman, United States; Abdallah, Jalal Mohamad, Department of Physics, The University of Texas at Arlington, Arlington, United States; Abdinov, O. B., Azerbaijan National Academy of Sciences, Baku, Azerbaijan; Abeloos, Baptiste, Laboratoire de l'Accélérateur Linéaire, Orsay, France; Abidi, Syed Hani, University of Toronto, Toronto, Canada; AbouZeid, O. S., Santa Cruz Institute for Particle Physics, Santa Cruz, United States; Abraham, Nicola L., University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Tel Aviv University, Tel Aviv-Yafo, IsraelThe electroweak production and subsequent decay of single top quarks in the t-channel is determined by the properties of the Wtb vertex, which can be described by the complex parameters of an effective Lagrangian. An analysis of a triple-differential decay rate in t-channel production is used to simultaneously determine five generalised helicity fractions and phases, as well as the polarisation of the produced top quark. The complex parameters are then constrained. This analysis is based on 20.2 fb−1 of proton-proton collision data at a centre-of-mass energy of 8 TeV collected with the ATLAS detector at the LHC. The fraction of decays containing transversely polarised W bosons is measured to be f1 = 0.30 ± 0.05. The phase between amplitudes for transversely and longitudinally polarised W bosons recoiling against left-handed b-quarks is measured to be δ− = 0.002π+ 0.017π + 0.016π, giving no indication of CP violation. The fractions of longitudinal or transverse W bosons accompanied by right-handed b-quarks are also constrained. Based on these measurements, limits are placed at 95% CL on the ratio of the complex coupling parameters Re [gR/VL ∈ [−0.12, 0.17] and Im [gR/VL ∈ [−0.07, 0.06]. Constraints are also placed on the ratios |VR/VL| and |gL/VL|. In addition, the polarisation of single top quarks in the t-channel is constrained to be P > 0.72 (95% CL). None of the above measurements make assumptions about the value of any of the other parameters or couplings and all of them are in agreement with the Standard Model.[Figure not available: see fulltext.]. © 2025 Elsevier B.V., All rights reserved.Publication Open Access Measurements of differential cross sections of top quark pair production in association with jets in pp collisions at √s=13 TeV using the ATLAS detector(Springer Verlag, 2018) Aaboud, M.; Aad, Georges; Abbott, Brad K.; Abdinov, O. B.; Abeloos, Baptiste; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; Abreu, Henso; Aaboud, M., National Energy Center of Nuclear Science and Technology, Rabat, Morocco; Aad, Georges, Johannes Gutenberg-Universität Mainz, Mainz, Germany; Abbott, Brad K., The Ohio State University, Columbus, United States; Abdinov, O. B., Azerbaijan National Academy of Sciences, Baku, Azerbaijan; Abeloos, Baptiste, Joint Laboratory of Optics, Olomouc, Czech Republic; Abidi, Syed Hani, Graduate School of Science and Technology, Tokyo Metropolitan University, Hachioji, Japan; AbouZeid, O. S., Charles University, Prague, Czech Republic; Abraham, Nicola L., SLAC National Accelerator Laboratory, Menlo Park, United States; Abramowicz, Halina, Elevter Andronikashvili Institute of Physics, Tbilisi, Georgia; Abreu, Henso, Academia Sinica, Institute Of Physics, Taipei, TaiwanMeasurements of differential cross sections of top quark pair production in association with jets by the ATLAS experiment at the LHC are presented. The measurements are performed as functions of the top quark transverse momentum, the transverse momentum of the top quark-antitop quark system and the out-of-plane transverse momentum using data from pp collisions at s=13 TeV collected by the ATLAS detector at the LHC in 2015 and corresponding to an integrated luminosity of 3.2 fb−1. The top quark pair events are selected in the lepton (electron or muon) + jets channel. The measured cross sections, which are compared to several predictions, allow a detailed study of top quark production.[Figure not available: see fulltext.] © 2025 Elsevier B.V., All rights reserved.Publication Open Access Search for top-quark decays t → Hq with 36 fb−1 of pp collision data at √s = 13 TeV with the ATLAS detector(Springer Verlag, 2019) Aaboud, M.; Aad, Georges; Abbott, Brad K.; Abbott, D. C.; Abdinov, O. B.; Abeloos, Baptiste; Abhayasinghe, D. K.; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Aaboud, M., National Energy Center of Nuclear Science and Technology, Rabat, Morocco; Aad, Georges, Johannes Gutenberg-Universität Mainz, Mainz, Germany; Abbott, Brad K., The Ohio State University, Columbus, United States; Abbott, D. C., School of Physics and Astronomy, The University of Manchester, Manchester, United Kingdom; Abdinov, O. B., Azerbaijan National Academy of Sciences, Baku, Azerbaijan; Abeloos, Baptiste, Joint Laboratory of Optics, Olomouc, Czech Republic; Abhayasinghe, D. K., Department of Experimental Particle Physics, Univerza v Ljubljani, Ljubljana, Slovenia; Abidi, Syed Hani, Graduate School of Science and Technology, Tokyo Metropolitan University, Hachioji, Japan; AbouZeid, O. S., Université Clermont Auvergne, Clermont-Ferrand, France; Abraham, Nicola L., SLAC National Accelerator Laboratory, Menlo Park, United StatesA search for flavour-changing neutral current decays of a top quark into an up-type quark (q = u, c) and the Standard Model Higgs boson, t → Hq, is presented. The search is based on a dataset of pp collisions at s = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 36.1 fb−1. Two complementary analyses are performed to search for top-quark pair events in which one top quark decays into Wb and the other top quark decays into Hq, and target the H→ bb¯ and H → τ+τ− decay modes, respectively. The high multiplicity of b-quark jets, or the presence of hadronically decaying τ-leptons, is exploited in the two analyses respectively. Multivariate techniques are used to separate the signal from the background, which is dominated by top-quark pair production. No significant excess of events above the background expectation is found, and 95% CL upper limits on the t → Hq branching ratios are derived. The combination of these searches with ATLAS searches in diphoton and multilepton final states yields observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 1.1 × 10−3 (8.3 × 10−4) and 1.2 × 10−3 (8.3 × 10−4), respectively. The corresponding combined observed (expected) upper limits on the |λtcH| and |λtuH| couplings are 0.064 (0.055) and 0.066 (0.055), respectively.[Figure not available: see fulltext.] © 2025 Elsevier B.V., All rights reserved.Publication Open Access Measurement of the top-quark mass in tt¯ + 1-jet events collected with the ATLAS detector in pp collisions at √s = 8 TeV(Springer Science and Business Media Deutschland GmbH, 2019) Aad, Georges; Abbott, Brad K.; Abbott, D. C.; Abdinov, O. B.; Abed Abud, Adam; Abeling, Kira; Abhayasinghe, D. K.; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Aad, Georges, Centre de Physique des Particules de Marseille, Marseille, France; Abbott, Brad K., The University of Oklahoma, Norman, United States; Abbott, D. C., Department of Physics, University of Massachusetts Amherst, Amherst, United States; Abdinov, O. B., Azerbaijan National Academy of Sciences, Baku, Azerbaijan; Abed Abud, Adam, Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, Pavia, Italy, Università degli Studi di Pavia, Pavia, Italy; Abeling, Kira, Georg-August-Universität Göttingen, Gottingen, Germany; Abhayasinghe, D. K., Department of Physics, Royal Holloway, University of London, Egham, United Kingdom; Abidi, Syed Hani, University of Toronto, Toronto, Canada; AbouZeid, O. S., Niels Bohr Institutet, Copenhagen, Denmark; Abraham, Nicola L., University of Sussex, Brighton, United KingdomA determination of the top-quark mass is presented using 20.2 fb−1 of 8 TeV proton-proton collision data produced by the Large Hadron Collider and collected by the ATLAS experiment. The normalised differential cross section of top-quark pair production in association with an energetic jet is measured in the lepton+jets final state and unfolded to parton and particle levels. The unfolded distribution at parton level can be described using next-to-leading-order QCD predictions in terms of either the top-quark pole mass or the running mass as defined in the (modified) minimal subtraction scheme. A comparison between the experimental distribution and the theoretical prediction allows the top-quark mass to be extracted in the two schemes. The value obtained for the pole-mass scheme is: mtpole=171.1±0.4(stat)±0.9(syst)−0.3+0.7(theo)GeV The extracted value in the running-mass scheme is: mt(mt)=162.9±0.5(stat)±1.0(syst)−1.2+2.1(theo)GeV. The results for the top-quark mass using the two schemes are consistent, when translated from one scheme to the other. [Figure not available: see fulltext.] © 2025 Elsevier B.V., All rights reserved.