Araştırma Çıktıları | WoS | Scopus | TR-Dizin | PubMed
Permanent URI for this communityhttps://hdl.handle.net/20.500.14719/1741
Browse
44 results
Search Results
Publication Open Access Fluctuations of anisotropic flow in Pb+Pb collisions at √sNN = 5.02 TeV with the ATLAS detector(Springer Science and Business Media Deutschland GmbH, 2020) Aaboud, M.; Aad, Georges; Abbott, Brad K.; Abbott, D. C.; Abdinov, O. B.; Abed Abud, Adam; Abhayasinghe, D. K.; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; 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; 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; 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 KingdomMulti-particle azimuthal cumulants are measured as a function of centrality and transverse momentum using 470 μb−1 of Pb+Pb collisions at sNN = 5.02 TeV with the ATLAS detector at the LHC. These cumulants provide information on the event-by-event fluctuations of harmonic flow coefficients vn and correlated fluctuations between two harmonics vn and vm. For the first time, a non-zero four-particle cumulant is observed for dipolar flow, v1. The four-particle cumulants for elliptic flow, v2, and triangular flow, v3, exhibit a strong centrality dependence and change sign in ultra-central collisions. This sign change is consistent with significant non-Gaussian fluctuations in v2 and v3. The four-particle cumulant for quadrangular flow, v4, is found to change sign in mid-central collisions. Correlations between two harmonics are studied with three- and four-particle mixed-harmonic cumulants, which indicate an anti-correlation between v2 and v3, and a positive correlation between v2 and v4. These correlations decrease in strength towards central collisions and either approach zero or change sign in ultra-central collisions. To investigate the possible flow fluctuations arising from intrinsic centrality or volume fluctuations, the results are compared between two different event classes used for centrality definitions. In peripheral and mid-central collisions where the cumulant signals are large, only small differences are observed. In ultra-central collisions, the differences are much larger and transverse momentum dependent. These results provide new information to disentangle flow fluctuations from the initial and final states, as well as new insights on the influence of centrality fluctuations. [Figure not available: see fulltext.]. © 2025 Elsevier B.V., All rights reserved.Publication Open Access Measurement of J/ψ production in association with a W ± boson with pp data at 8 TeV(Springer Science and Business Media Deutschland GmbH, 2020) 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., 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; Abbott, D. C., Department of Physics, University of Massachusetts Amherst, Amherst, United States; Abdinov, O. B., Azerbaijan National Academy of Sciences, Baku, Azerbaijan; Abeloos, Baptiste, Laboratoire de l'Accélérateur Linéaire, Orsay, France; 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 measurement of the production of a prompt J/ψ meson in association with a W± boson with W± → μν and J/ψ → μ+μ− is presented for J/ψ transverse momenta in the range 8.5–150 GeV and rapidity |yJ/ψ| < 2.1 using ATLAS data recorded in 2012 at the LHC. The data were taken at a proton-proton centre-of-mass energy of s = 8 TeV and correspond to an integrated luminosity of 20.3 fb−1. The ratio of the prompt J/ψ plus W± cross-section to the inclusive W± cross-section is presented as a differential measurement as a function of J/ψ transverse momenta and compared with theoretical predictions using different double-parton-scattering cross-sections. [Figure not available: see fulltext.]. © 2025 Elsevier B.V., All rights reserved.Publication Metadata only Measurement of differential cross sections for single diffractive dissociation in √s = 8 TeV pp collisions using the ATLAS ALFA spectrometer(Springer Science and Business Media Deutschland GmbH, 2020) 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, Aix Marseille Université, Marseille, France; Abbott, Brad K., Homer L. Dodge Department of Physics and Astronomy, 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, Department of Physics, Università degli Studi di Pavia, Pavia, Italy; Abeling, Kira, Institute of Physics, Georg-August-Universität Göttingen, Gottingen, Germany; Abhayasinghe, D. K., Department of Physics, Royal Holloway, University of London, Egham, United Kingdom; Abidi, Syed Hani, Department of Physics, University of Toronto, Toronto, Canada; AbouZeid, O. S., Niels Bohr Institutet, Copenhagen, Denmark; Abraham, Nicola L., Department of Physics and Astronomy, University of Sussex, Brighton, United KingdomA dedicated sample of Large Hadron Collider proton-proton collision data at centre-of-mass energy s = 8 TeV is used to study inclusive single diffractive dissociation, pp → X p. The intact final-state proton is reconstructed in the ATLAS ALFA forward spectrometer, while charged particles from the dissociated system X are measured in the central detector components. The fiducial range of the measurement is −4.0 < log10ξ < −1.6 and 0.016 < |t| < 0.43 GeV2, where ξ is the proton fractional energy loss and t is the squared four-momentum transfer. The total cross section integrated across the fiducial range is 1.59 ± 0.13 mb. Cross sections are also measured differentially as functions of ξ, t, and ∆η, a variable that characterises the rapidity gap separating the proton and the system X. The data are consistent with an exponential t dependence, dσ/dt ∝ eBt with slope parameter B = 7.65 ± 0.34 GeV−2. Interpreted in the framework of triple Regge phenomenology, the ξ dependence leads to a pomeron intercept of α(0) = 1.07 ± 0.09. [Figure not available: see fulltext.] © 2020 Elsevier B.V., All rights reserved.Publication Open Access Measurement of the Z(→ ℓ + ℓ −)γ production cross-section in pp collisions at √s = 13 TeV with the ATLAS detector(Springer Science and Business Media Deutschland GmbH, 2020) Aad, Georges; Abbott, Brad K.; Abbott, D. C.; Abed Abud, Adam; Abeling, Kira; Abhayasinghe, D. K.; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; 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; 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 Kingdom; Abramowicz, Halina, Tel Aviv University, Tel Aviv-Yafo, IsraelThe production of a prompt photon in association with a Z boson is studied in proton-proton collisions at a centre-of-mass energy s = 13 TeV. The analysis uses a data sample with an integrated luminosity of 139 fb−1 collected by the ATLAS detector at the LHC from 2015 to 2018. The production cross-section for the process pp → ℓ+ℓ−γ + X (ℓ = e, μ) is measured within a fiducial phase-space region defined by kinematic requirements on the photon and the leptons, and by isolation requirements on the photon. An experimental precision of 2.9% is achieved for the fiducial cross-section. Differential cross-sections are measured as a function of each of six kinematic variables characterising the ℓ+ℓ−γ system. The data are compared with theoretical predictions based on next-to-leading-order and next-to-next-to-leading-order perturbative QCD calculations. The impact of next-to-leading-order electroweak corrections is also considered. [Figure not available: see fulltext.]. © 2025 Elsevier B.V., All rights reserved.Publication Open Access Search for new resonances in mass distributions of jet pairs using 139 fb −1 of pp collisions at √s = 13 TeV with the ATLAS detector(Springer, 2020) Aad, Georges; Abbott, Brad K.; Abbott, D. C.; Abed Abud, Adam; Abeling, Kira; Abhayasinghe, D. K.; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; 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; Abbott, D. C., Department of Physics, University of Massachusetts Amherst, Amherst, United States; Abed Abud, Adam, Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, Pavia, Italy, Department of Physics, Università degli Studi di Pavia, Pavia, Italy; Abeling, Kira, Institute of Physics, Georg-August-Universität Göttingen, Gottingen, Germany; Abhayasinghe, D. K., Royal Holloway, University of London, Egham, United Kingdom; Abidi, Syed Hani, Department of Physics, University of Toronto, Toronto, Canada; AbouZeid, O. S., Niels Bohr Institutet, Copenhagen, Denmark; Abraham, Nicola L., University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv-Yafo, IsraelA search for new resonances decaying into a pair of jets is reported using the dataset of proton-proton collisions recorded at s = 13 TeV with the ATLAS detector at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of 139 fb−1. The distribution of the invariant mass of the two leading jets is examined for local excesses above a data-derived estimate of the Standard Model background. In addition to an inclusive dijet search, events with jets identified as containing b-hadrons are examined specifically. No significant excess of events above the smoothly falling background spectra is observed. The results are used to set cross-section upper limits at 95% confidence level on a range of new physics scenarios. Model-independent limits on Gaussian-shaped signals are also reported. The analysis looking at jets containing b-hadrons benefits from improvements in the jet flavour identification at high transverse momentum, which increases its sensitivity relative to the previous analysis beyond that expected from the higher integrated luminosity. [Figure not available: see fulltext.] © 2020 Elsevier B.V., All rights reserved.Publication Open Access Measurement of isolated-photon plus two-jet production in pp collisions at √s = 13 TeV with the ATLAS detector(Springer Science and Business Media Deutschland GmbH, 2020) Aad, Georges; Abbott, Brad K.; Abbott, D. C.; Abed Abud, Adam; Abeling, Kira; Abhayasinghe, D. K.; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; 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; 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 Kingdom; Abramowicz, Halina, Tel Aviv University, Tel Aviv-Yafo, IsraelThe dynamics of isolated-photon plus two-jet production in pp collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset corresponding to an integrated luminosity of 36.1 fb−1. Cross sections are measured as functions of a variety of observables, including angular correlations and invariant masses of the objects in the final state, γ + jet + jet. Measurements are also performed in phase-space regions enriched in each of the two underlying physical mechanisms, namely direct and fragmentation processes. The measurements cover the range of photon (jet) transverse momenta from 150 GeV (100 GeV) to 2 TeV. The tree-level plus parton-shower predictions from Sherpa and Pythia as well as the next-to-leading-order QCD predictions from Sherpa are compared with the measurements. The next-to-leading-order QCD predictions describe the data adequately in shape and normalisation except for regions of phase space such as those with high values of the invariant mass or rapidity separation of the two jets, where the predictions overestimate the data. [Figure not available: see fulltext.] © 2025 Elsevier B.V., All rights reserved.Publication Open Access Search for squarks and gluinos in final states with same-sign leptons and jets using 139 fb −1 of data collected with the ATLAS detector(Springer Science and Business Media Deutschland GmbH, 2020) Aad, Georges; Abbott, Brad K.; Abbott, D. C.; Abed Abud, Adam; Abeling, Kira; Abhayasinghe, D. K.; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; 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; 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 Kingdom; Abramowicz, Halina, Tel Aviv University, Tel Aviv-Yafo, IsraelA search for supersymmetric partners of gluons and quarks is presented, involving signatures with jets and either two isolated leptons (electrons or muons) with the same electric charge, or at least three isolated leptons. A data sample of proton-proton collisions at s = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018, corresponding to a total integrated luminosity of 139 fb−1, is used for the search. No significant excess over the Standard Model expectation is observed. The results are interpreted in simplified supersymmetric models featuring both R-parity conservation and R-parity violation, raising the exclusion limits beyond those of previous ATLAS searches to 1600 GeV for gluino masses and 750 GeV for bottom and top squark masses in these scenarios. [Figure not available: see fulltext.] © 2025 Elsevier B.V., All rights reserved.Publication Open Access Search for dijet resonances in events with an isolated charged lepton using √s = 13 TeV proton-proton collision data collected by the ATLAS detector(Springer, 2020) Aad, Georges; Abbott, Brad K.; Abbott, D. C.; Abed Abud, Adam; Abeling, Kira; Abhayasinghe, D. K.; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; 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; Abbott, D. C., Department of Physics, University of Massachusetts Amherst, Amherst, United States; Abed Abud, Adam, Organisation Européenne pour la Recherche Nucléaire, Geneva, Switzerland; Abeling, Kira, Institute of Physics, Georg-August-Universität Göttingen, Gottingen, Germany; Abhayasinghe, D. K., Royal Holloway, University of London, Egham, United Kingdom; Abidi, Syed Hani, Department of Physics, University of Toronto, Toronto, Canada; AbouZeid, O. S., Niels Bohr Institutet, Copenhagen, Denmark; Abraham, Nicola L., University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv-Yafo, IsraelA search for dijet resonances in events with at least one isolated charged lepon is performed using 139 fb−1 of s = 13 TeV proton-proton collision data recorded by the ATLAS detector at the LHC. The dijet invariant-mass (mjj) distribution constructed from events with at least one isolated electron or muon is searched in the region 0.22 < mjj< 6.3 TeV for excesses above a smoothly falling background from Standard Model processes. Triggering based on the presence of a lepton in the event reduces limitations imposed by minimum transverse momentum thresholds for triggering on jets. This approach allows smaller dijet invariant masses to be probed than in inclusive dijet searches, targeting a variety of new-physics models, for example ones in which a new state is produced in association with a leptonically decaying W or Z boson. No statistically significant deviation from the Standard Model background hypothesis is found. Limits on contributions from generic Gaussian signals with widths ranging from that determined by the detector resolution up to 15% of the resonance mass are obtained for dijet invariant masses ranging from 0.25 TeV to 6 TeV. Limits are set also in the context of several scenarios beyond the Standard Model, such as the Sequential Standard Model, a technicolor model, a charged Higgs boson model and a simplified Dark Matter model. [Figure not available: see fulltext.] © 2020 Elsevier B.V., All rights reserved.Publication Open Access Measurements of the production cross-section for a Z boson in association with b-jets in proton-proton collisions at √s = 13 TeV with the ATLAS detector(Springer, 2020) Aad, Georges; Abbott, Brad K.; Abbott, D. C.; Abed Abud, Adam; Abeling, Kira; Abhayasinghe, D. K.; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; 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; Abbott, D. C., Department of Physics, University of Massachusetts Amherst, Amherst, United States; Abed Abud, Adam, Organisation Européenne pour la Recherche Nucléaire, Geneva, Switzerland; Abeling, Kira, Institute of Physics, Georg-August-Universität Göttingen, Gottingen, Germany; Abhayasinghe, D. K., Royal Holloway, University of London, Egham, United Kingdom; Abidi, Syed Hani, Department of Physics, University of Toronto, Toronto, Canada; AbouZeid, O. S., Niels Bohr Institutet, Copenhagen, Denmark; Abraham, Nicola L., University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv-Yafo, IsraelThis paper presents a measurement of the production cross-section of a Z boson in association with b-jets, in proton-proton collisions at s = 13 TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 35.6 fb−1. Inclusive and differential cross-sections are measured for events containing a Z boson decaying into electrons or muons and produced in association with at least one or at least two b-jets with transverse momentum pT> 20 GeV and rapidity |y| < 2.5. Predictions from several Monte Carlo generators based on leading-order (LO) or next-to-leading-order (NLO) matrix elements interfaced with a parton-shower simulation and testing different flavour schemes for the choice of initial-state partons are compared with measured cross-sections. The 5-flavour number scheme predictions at NLO accuracy agree better with data than 4-flavour number scheme ones. The 4-flavour number scheme predictions underestimate data in events with at least one b-jet. [Figure not available: see fulltext.] © 2020 Elsevier B.V., All rights reserved.Publication Open Access Search for the HH → bb¯ bb¯ process via vector-boson fusion production using proton-proton collisions at √s = 13 TeV with the ATLAS detector(Springer Science and Business Media Deutschland GmbH, 2020) Aad, Georges; Abbott, Brad K.; Abbott, D. C.; Abed Abud, Adam; Abeling, Kira; Abhayasinghe, D. K.; Abidi, Syed Hani; AbouZeid, O. S.; Abraham, Nicola L.; Abramowicz, Halina; 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; 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 Kingdom; Abramowicz, Halina, Tel Aviv University, Tel Aviv-Yafo, IsraelA search for Higgs boson pair production via vector-boson fusion (VBF) in the bb¯ bb¯ final state is carried out with the ATLAS experiment using 126 fb−1 of proton- proton collision data delivered at s = 13 TeV by the Large Hadron Collider. This search is sensitive to VBF production of additional heavy bosons that may decay into Higgs boson pairs, and in a non-resonant topology it can constrain the quartic coupling between the Higgs bosons and vector bosons. No significant excess relative to the Standard Model expectation is observed, and limits on the production cross-section are set at the 95% confidence level for a heavy scalar resonance in the context of an extended Higgs sector, and for non-resonant Higgs boson pair production. Interpretation in terms of the coupling between a Higgs boson pair and two vector bosons is also provided: coupling values normalised to the Standard Model expectation of κ2V< −0.76 and κ2V> 2.90 are excluded at the 95% confidence level in data. [Figure not available: see fulltext.] © 2025 Elsevier B.V., All rights reserved.