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Publication Open Access Charged-particle distributions in pp interactions at √s = 8 TeV measured with the ATLAS detector(Springer Science and Business Media Deutschland GmbH, 2016) Aad, Georges; Abbott, Brad K.; Abdallah, Jalal Mohamad; Abdinov, O. B.; Abeloos, Baptiste; Aben, R.; Abolins, Maris A.; 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; Abdallah, Jalal Mohamad, Academia Sinica, Institute Of Physics, Taipei, Taiwan; 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; Abolins, Maris A., Department of Physics and Astronomy, Michigan State University, East Lansing, United States; 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, IsraelThis paper presents measurements of distributions of charged particles which are produced in proton-proton collisions at a centre-of-mass energy of √s = 8 TeV and recorded by the ATLAS detector at the LHC. A special dataset recorded in 2012 with a small number of interactions per beam crossing (below 0.004) and corresponding to an integrated luminosity of 160 µb-1 was used. A minimum-bias trigger was utilised to select a data sample of more than 9 million collision events. The multiplicity, pseudorapidity, and transverse momentum distributions of charged particles are shown in different regions of kinematics and chargedparticle multiplicity, including measurements of final states at high multiplicity. The results are corrected for detector effects and are compared to the predictions of various Monte Carlo event generator models which simulate the full hadronic final state. © 2024 Elsevier B.V., All rights reserved.Publication Metadata only Search for scalar leptoquarks in pp collisions at √S = 13TeV with the ATLAS experiment(Institute of Physics, 2016) 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., 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, University of Iowa, Iowa City, 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., University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Tel Aviv University, Tel Aviv-Yafo, IsraelAn inclusive search for a new-physics signature of lepton-jet resonances has been performed by the ATLAS experiment. Scalar leptoquarks, pair-produced in pp collisions at s √S13 TeV at the large hadron collider, have been considered. An integrated luminosity of 3.2 fb−1, corresponding to the full 2015 dataset was used. First (second) generation leptoquarks were sought in events with two electrons (muons) and two or more jets. The observed event yield in each channel is consistent with Standard Model background expectations. The observed (expected) lower limits on the leptoquark mass at 95% confidence level are 1100 and 1050 GeV (1160 and 1040 GeV) for first and second generation leptoquarks, respectively, assuming a branching ratio into a charged lepton and a quark of 100%. Upper limits on the aforementioned branching ratio are also given as a function of leptoquark mass. Compared with the results of earlier ATLAS searches, the sensitivity is increased for leptoquark masses above 860 GeV, and the observed exclusion limits confirm and extend the published results. © 2022 Elsevier B.V., All rights reserved.Publication Open Access Measurement of the ZZ production cross section in pp collisions at √s = 13 TeV with the ATLAS detector(American Physical Society revtex@aps.org, 2016) Aad, Georges; Abbott, Brad K.; Abdallah, Jalal Mohamad; Abdinov, O. B.; Abeloos, Baptiste; Aben, R.; Abolins, Maris A.; AbouZeid, O. S.; Abramowicz, Halina; Abreu, Henso; 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, Academia Sinica, Institute Of Physics, Taipei, Taiwan; 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; Abolins, Maris A., Department of Physics and Astronomy, Michigan State University, East Lansing, United States; AbouZeid, O. S., Santa Cruz Institute for Particle Physics, Santa Cruz, United States; Abramowicz, Halina, Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv-Yafo, Israel; Abreu, Henso, Department of Physics, Technion - Israel Institute of Technology, Haifa, IsraelThe ZZ production cross section in proton-proton collisions at 13 TeV center-of-mass energy is measured using 3.2 fb-1 of data recorded with the ATLAS detector at the Large Hadron Collider. The considered Z boson candidates decay to an electron or muon pair of mass 66-116 GeV. The cross section is measured in a fiducial phase space reflecting the detector acceptance. It is also extrapolated to a total phase space for Z bosons in the same mass range and of all decay modes, giving 16.7-2.0+2.2(stat)+0.9-0.7(syst)+1.0-0.7(lumi) pb. The results agree with standard model predictions. © 2019 Elsevier B.V., All rights reserved.Publication Open Access Muon reconstruction performance of the ATLAS detector in proton–proton collision data at s=13 TeV(Springer Science and Business Media, LLC, 2016) Atlas Collaboration; Aad, Georges; Abbott, Brad K.; Abdallah, Jalal Mohamad; Abdinov, O. B.; Abeloos, Baptiste; Aben, R.; Abolins, Maris A.; AbouZeid, O. S.; Abraham, Nicola L.; Atlas Collaboration, null, Organisation Européenne pour la Recherche Nucléaire, Geneva, Switzerland; Aad, Georges, Centre de Physique des Particules de Marseille, Marseille, France; Abbott, Brad K., The University of Oklahoma, Norman, United States; Abdallah, Jalal Mohamad, University of Iowa, Iowa City, 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; Abolins, Maris A., Department of Physics and Astronomy, Michigan State University, East Lansing, United States; AbouZeid, O. S., Santa Cruz Institute for Particle Physics, Santa Cruz, United States; Abraham, Nicola L., University of Sussex, Brighton, United KingdomThis article documents the performance of the ATLAS muon identification and reconstruction using the LHC dataset recorded at s=13 TeV in 2015. Using a large sample of J/ ψ→ μμ and Z→ μμ decays from 3.2 fb- 1 of pp collision data, measurements of the reconstruction efficiency, as well as of the momentum scale and resolution, are presented and compared to Monte Carlo simulations. The reconstruction efficiency is measured to be close to 99% over most of the covered phase space (| η| < 2.5 and 5 < pT< 100 GeV). The isolation efficiency varies between 93 and 100% depending on the selection applied and on the momentum of the muon. Both efficiencies are well reproduced in simulation. In the central region of the detector, the momentum resolution is measured to be 1.7% (2.3%) for muons from J/ ψ→ μμ (Z→ μμ) decays, and the momentum scale is known with an uncertainty of 0.05%. In the region | η| > 2.2 , the pT resolution for muons from Z→ μμ decays is 2.9% while the precision of the momentum scale for low-pT muons from J/ ψ→ μμ decays is about 0.2%. © 2024 Elsevier B.V., All rights reserved.Publication Open Access Measurement of the charged-particle multiplicity inside jets from √s = 8 TeV pp collisions with the ATLAS detector(Springer Science and Business Media, LLC, 2016) Atlas Collaboration; Aad, Georges; Abbott, Brad K.; Abdallah, Jalal Mohamad; Abdinov, O. B.; Abeloos, Baptiste; Aben, R.; Abolins, Maris A.; AbouZeid, O. S.; Abraham, Nicola L.; Atlas Collaboration, null, Organisation Européenne pour la Recherche Nucléaire, Geneva, Switzerland; Aad, Georges, Centre de Physique des Particules de Marseille, Marseille, France; Abbott, Brad K., The University of Oklahoma, Norman, United States; Abdallah, Jalal Mohamad, Academia Sinica, Institute Of Physics, Taipei, Taiwan; 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; Abolins, Maris A., Department of Physics and Astronomy, Michigan State University, East Lansing, United States; AbouZeid, O. S., Santa Cruz Institute for Particle Physics, Santa Cruz, United States; Abraham, Nicola L., University of Sussex, Brighton, United KingdomThe number of charged particles inside jets is a widely used discriminant for identifying the quark or gluon nature of the initiating parton and is sensitive to both the perturbative and non-perturbative components of fragmentation. This paper presents a measurement of the average number of charged particles with >500 pT> 500 {\mathrm{MeV}} MeV inside high-momentum jets in dijet events using 20.3 fb-1 of data recorded with the ATLAS detector in pp collisions at √s = 8 TeV collisions at the LHC. The jets considered have transverse momenta from 50 GeV up to and beyond 1.5 TeV. The reconstructed charged-particle track multiplicity distribution is unfolded to remove distortions from detector effects and the resulting charged-particle multiplicity is compared to several models. Furthermore, quark and gluon jet fractions are used to extract the average charged-particle multiplicity for quark and gluon jets separately. © 2024 Elsevier B.V., All rights reserved.Publication Open Access Search for Higgs and Z Boson Decays to φγ with the ATLAS Detector(American Physical Society revtex@aps.org, 2016) 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, University of Iowa, Iowa City, 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., 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 the decays of the Higgs and Z bosons to a φ meson and a photon is performed with a pp collision data sample corresponding to an integrated luminosity of 2.7 fb-1 collected at s=13 TeV with the ATLAS detector at the LHC. No significant excess of events is observed above the background, and 95% confidence level upper limits on the branching fractions of the Higgs and Z boson decays to φγ of 1.4×10-3 and 8.3×10-6, respectively, are obtained. © 2020 Elsevier B.V., All rights reserved.Publication Open Access Measurement of the Inelastic Proton-Proton Cross Section at √s=13 TeV with the ATLAS Detector at the LHC(American Physical Society revtex@aps.org, 2016) 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, University of Iowa, Iowa City, 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., University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv-Yafo, IsraelThis Letter presents a measurement of the inelastic proton-proton cross section using 60 μb-1 of pp collisions at a center-of-mass energy s of 13 TeV with the ATLAS detector at the LHC. Inelastic interactions are selected using rings of plastic scintillators in the forward region (2.07<|η|<3.86) of the detector. A cross section of 68.1±1.4 mb is measured in the fiducial region ξ=MX2/s>10-6, where MX is the larger invariant mass of the two hadronic systems separated by the largest rapidity gap in the event. In this ξ range the scintillators are highly efficient. For diffractive events this corresponds to cases where at least one proton dissociates to a system with MX>13 GeV. The measured cross section is compared with a range of theoretical predictions. When extrapolated to the full phase space, a cross section of 78.1±2.9 mb is measured, consistent with the inelastic cross section increasing with center-of-mass energy. © 2020 Elsevier B.V., All rights reserved.Publication Open Access A measurement of material in the ATLAS tracker using secondary hadronic interactions in 7TeV pp collisions(Institute of Physics Publishing michael.roberts@iop.org, 2016) 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, Centre de Physique des Particules de Marseille, Marseille, France; Abbott, Brad K., Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, Norman, United States; Abdallah, Jalal Mohamad, University of Iowa, Iowa City, 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, IsraelKnowledge of the material in the ATLAS inner tracking detector is crucial in understanding the reconstruction of charged-particle tracks, the performance of algorithms that identify jets containing b-hadrons and is also essential to reduce background in searches for exotic particles that can decay within the inner detector volume. Interactions of primary hadrons produced in pp collisions with the material in the inner detector are used to map the location and amount of this material. The hadronic interactions of primary particles may result in secondary vertices, which in this analysis are reconstructed by an inclusive vertex-finding algorithm. Data were collected using minimum-bias triggers by the ATLAS detector operating at the LHC during 2010 at centre-of-mass energy √s = 7TeV, and correspond to an integrated luminosity of 19nb-1. Kinematic properties of these secondary vertices are used to study the validity of the modelling of hadronic interactions in simulation. Secondary-vertex yields are compared between data and simulation over a volume of about 0.7 m3 around the interaction point, and agreement is found within overall uncertainties. © 2017 Elsevier B.V., All rights reserved.Publication Open Access Luminosity determination in pp collisions at √s = 8 TeV using the ATLAS detector at the LHC(Springer Science and Business Media, LLC, 2016) 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., 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, University of Iowa, Iowa City, 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., University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Tel Aviv University, Tel Aviv-Yafo, IsraelThe luminosity determination for the ATLAS detector at the LHC during pp collisions at s= 8 TeV in 2012 is presented. The evaluation of the luminosity scale is performed using several luminometers, and comparisons between these luminosity detectors are made to assess the accuracy, consistency and long-term stability of the results. A luminosity uncertainty of δL/ L= ± 1.9 % is obtained for the 22.7fb-1 of pp collision data delivered to ATLAS at s= 8 TeV in 2012. © 2024 Elsevier B.V., All rights reserved.Publication Open Access A measurement of the calorimeter response to single hadrons and determination of the jet energy scale uncertainty using LHC Run-1 pp-collision data with the ATLAS detector(Springer Science and Business Media, LLC, 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., 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, University of Iowa, Iowa City, 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., University of Sussex, Brighton, United Kingdom; Abramowicz, Halina, Tel Aviv University, Tel Aviv-Yafo, IsraelA measurement of the calorimeter response to isolated charged hadrons in the ATLAS detector at the LHC is presented. This measurement is performed with 3.2 nb- 1 of proton–proton collision data at s=7 TeV from 2010 and 0.1 nb- 1 of data at s=8 TeV from 2012. A number of aspects of the calorimeter response to isolated hadrons are explored. After accounting for energy deposited by neutral particles, there is a 5% discrepancy in the modelling, using various sets of Geant4 hadronic physics models, of the calorimeter response to isolated charged hadrons in the central calorimeter region. The description of the response to anti-protons at low momenta is found to be improved with respect to previous analyses. The electromagnetic and hadronic calorimeters are also examined separately, and the detector simulation is found to describe the response in the hadronic calorimeter well. The jet energy scale uncertainty and correlations in scale between jets of different momenta and pseudorapidity are derived based on these studies. The uncertainty is 2–5% for jets with transverse momenta above 2 TeV, where this method provides the jet energy scale uncertainty for ATLAS. © 2025 Elsevier B.V., All rights reserved.