Measurement of J/ψ production in association with a W ± boson with pp data at 8 TeV

A 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.]

Measurement of VH, H→bb¯ production as a function of the vector-boson transverse momentum in 13 TeV pp collisions with the ATLAS detector

Cross-sections of associated production of a Higgs boson decaying into bottom-quark pairs and an electroweak gauge boson, W or Z, decaying into leptons are measured as a function of the gauge boson transverse momentum. The measurements are performed in kinematic fiducial volumes defined in the `simplified template cross-section´ framework. The results are obtained using 79.8 fb−1 of proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. All measurements are found to be in agreement with the Standard Model predictions, and limits are set on the parameters of an effective Lagrangian sensitive to modifications of the Higgs boson couplings to the electroweak gauge bosons.Fil: Aaboud, M.. Université Mohamed; MarruecosFil: Aad, G.. Aix-Marseille Université; Francia. Centre National de la Recherche Scientifique; FranciaFil: Abbott, B.. University of Oklahoma; Estados UnidosFil: Abbott, D. C.. University of Oklahoma; Estados UnidosFil: Abdinov, O.. Azerbaijan Academy of Sciences; AzerbaiyánFil: Abed Abud, A.. Universita degli Studi di Pavia; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Abhayasinghe, D. K.. Royal Holloway University of London; Reino UnidoFil: Abidi, S. H.. University of Toronto; CanadáFil: AbouZeid, O. S.. Universidad de Copenhagen; DinamarcaFil: Abraham, N. L.. University of Sussex; Reino UnidoFil: Abramowicz, H.. Universitat Tel Aviv; IsraelFil: Abreu, H.. Technion - Israel Institute of Technology; IsraelFil: Abulaiti, Y.. Argonne National Laboratory; Estados UnidosFil: Acharya, B. S.. Istituto Nazionale di Fisica Nucleare; Italia. The Abdus Salam. International Centre for Theoretical Physics; Italia. King’s College London; Reino UnidoFil: Adachi, S.. University of Tokyo; JapónFil: Adam, L.. Universität Mainz; AlemaniaFil: Adam Bourdarios, C.. Université Paris-Sud; Francia. Universite Paris-Saclay; . Centre National de la Recherche Scientifique; FranciaFil: Adamczyk, L.. University of Science and Technology; PoloniaFil: Adamek, L.. University of Toronto; CanadáFil: Adelman, J.. Northern Illinois University; Estados UnidosFil: Adersberger, M.. Ludwig-Maximilians-Universität München; AlemaniaFil: Adiguzel, A.. Bogazici University; Turquía. Istanbul University; TurquíaFil: Adorni, S.. Université de Genève; FranciaFil: Adye, T.. Rutherford Appleton Laboratory; Reino UnidoFil: Affolder, A. A.. University of California Santa Cruz; Estados UnidosFil: Afik, Y.. Technion - Israel Institute of Technology; IsraelFil: Agapopoulou, C.. Université Paris-Sud; Francia. Centre National de la Recherche Scientifique; Francia. Universite Paris-Saclay;Fil: Agaras, M. N.. Université Clermont Auvergne; Francia. Centre National de la Recherche Scientifique; FranciaFil: Aggarwal, A.. Radboud Universiteit Nijmegen; Países BajosFil: Arduh, Francisco Anuar. Cern - European Organization for Nuclear Research; Suiza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentin

Search for Magnetic Monopoles and Stable High-Electric-Charge Objects in 13 Tev Proton-Proton Collisions with the ATLAS Detector.

A search for magnetic monopoles and high-electric-charge objects is presented using 34.4  fb^{-1} of 13 TeV pp collision data collected by the ATLAS detector at the LHC during 2015 and 2016. The considered signature is based upon high ionization in the transition radiation tracker of the inner detector associated with a pencil-shape energy deposit in the electromagnetic calorimeter. The data were collected by a dedicated trigger based on the tracker high-threshold hit capability. The results are interpreted in models of Drell-Yan pair production of stable particles with two spin hypotheses (0 and 1/2) and masses ranging from 200 to 4000 GeV. The search improves by approximately a factor of 5 the constraints on the direct production of magnetic monopoles carrying one or two Dirac magnetic charges and stable objects with electric charge in the range 20≤|z|≤60 and extends the charge range to 60<|z|≤100

Measurement of the four-lepton invariant mass spectrum in 13 TeV proton-proton collisions with the ATLAS detector

A measurement of the four-lepton invariant mass spectrum is made with the ATLAS detector, using an integrated luminosity of 36.1 fb−1 of proton–proton collisions at √ s = 13 TeV delivered by the Large Hadron Collider. The differential cross-section is measured for events containing two same-flavour opposite-sign lepton pairs. It exhibits a rich structure, with different mass regions dominated in the Standard Model by single Z boson production, Higgs boson production, and Z boson pair production, and non-negligible interference effects at high invariant masses. The measurement is compared with state-of-the-art Standard Model calculations, which are found to be consistent with the data. These calculations are used to interpret the data in terms of gg → Z Z → 4` and Z → 4` subprocesses, and to place constraints on a possible contribution from physics beyond the Standard Model.Fil: Aaboud, M.. Université Mohamed Premier; MarruecosFil: Aad, G.. Aix-Marseille Université; Francia. Centre National de la Recherche Scientifique; FranciaFil: Abbott, B.. University of Oklahoma; Estados UnidosFil: Abdinov, O.. Azerbaijan Academy of Sciences; AzerbaiyánFil: Abeloos, B.. Université Paris-Sud; Francia. Universite Paris-Saclay; . Centre National de la Recherche Scientifique; FranciaFil: Abhayasinghe, D. K.. Royal Holloway University of London; Reino UnidoFil: Abidi, S. H.. University of Toronto; CanadáFil: AbouZeid, O. S.. Universidad de Copenhagen; DinamarcaFil: Abraham, N. L.. University of Sussex; Reino UnidoFil: Abramowicz, H.. Universitat Tel Aviv; IsraelFil: Abreu, H.. Technion - Israel Institute of Technology; IsraelFil: Abulaiti, Y.. Argonne National Laboratory; Estados UnidosFil: Acharya, B. S.. King’s College London; Reino Unido. Istituto Nazionale di Fisica Nucleare; Italia. The Abdus Salam. International Centre for Theoretical Physics; ItaliaFil: Adachi, S.. University of Tokyo; JapónFil: Adam, L.. Universität Mainz; AlemaniaFil: Adamczyk, L.. AGH University of Science and Technology; PoloniaFil: Adelman, J.. Northern Illinois University; Estados UnidosFil: Adersberger, M.. Ludwig-Maximilians-Universität München; AlemaniaFil: Adiguzel, A.. Istanbul University; Turquía. Bogazici University; TurquíaFil: Adye, T.. Rutherford Appleton Laboratory; Reino UnidoFil: Affolder, A. A.. University of California Santa Cruz; Estados UnidosFil: Afik, Y.. Technion - Israel Institute of Technology; IsraelFil: Agheorghiesei, C.. Alexandru Ioan Cuza University of Iasi; RumaniaFil: Aguilar Saavedra, J. A.. Universidad de Granada; España. Laboratório de Instrumentação e Física Experimental de Partículas; Portugal. Universidad Autónoma de Madrid; EspañaFil: Ahmadov, F.. Azerbaijan Academy of Sciences; AzerbaiyánFil: Aielli, G.. Università di Roma Tor Vergata; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Akatsuka, S.. Kyoto University; JapónFil: Åkesson, T. P. A.. Lunds universitet; SueciaFil: Akilli, E.. Université de Genève; SuizaFil: Arduh, Francisco Anuar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Cern - European Organization for Nuclear Research; Suiz

Study of ordered hadron chains with the ATLAS detector

9

Operation of the ATLAS trigger system in run 2

The ATLAS experiment at the Large Hadron Collider employs a two-level triggersystem to record data at an average rate of 1 kHz from physics collisions,starting from an initial bunch crossing rate of 40 MHz. During the LHC Run 2(2015-2018), the ATLAS trigger system operated successfully with excellentperformance and flexibility by adapting to the various run conditionsencountered and has been vital for the ATLAS Run-2 physics programme. Forproton-proton running, approximately 1500 individual event selections wereincluded in a trigger menu which specified the physics signatures and selectionalgorithms used for the data-taking, and the allocated event rate andbandwidth. The trigger menu must reflect the physics goals for a given datacollection period, taking into account the instantaneous luminosity of the LHCand limitations from the ATLAS detector readout, online processing farm, andoffline storage. This document discusses the operation of the ATLAS triggersystem during the nominal proton-proton data collection in Run 2 with examplesof special data-taking runs. Aspects of software validation, evolution of thetrigger selection algorithms during Run 2, monitoring of the trigger system anddata quality as well as trigger configuration are presented.Fil: Aad, G.. Aix-Marseille Université; FranciaFil: Abbott, B.. Oklahoma State University; Estados UnidosFil: Abbott, D.C.. University of Massachusetts; Estados UnidosFil: Abed Abud, A.. Cern - European Organization for Nuclear Research; SuizaFil: Abeling, K.. Georg-August-Universität Göttingen; AlemaniaFil: Abhayasinghe, D.K.. Royal Holloway University of London; Reino UnidoFil: Abidi, S. H.. University of Toronto; CanadáFil: AbouZeid, O. S.. Czech Academy of Sciences; República ChecaFil: Abraham, N. L.. University of Sussex; Reino UnidoFil: Abramowicz, H.. Universitat Tel Aviv; IsraelFil: Abreu, H.. Technion - Israel Institute of Technology; IsraelFil: Abreu, R.. University of Oregon; Estados UnidosFil: Abulaiti, Y.. Argonne National Laboratory; Estados UnidosFil: Acharya, B. S.. Istituto Nazionale di Fisica Nucleare; Italia. The Abdus Salam. International Centre for Theoretical Physics; ItaliaFil: Achkak, B.. Georg-August-Universität Göttingen; AlemaniaFil: Adam, L.. University of Montreal; CanadáFil: Adam Bourdarios, C.. Universite Grenoble Alpes; Francia. Université Savoie Mont Blanc; FranciaFil: Adamczyk, L.. AGH University of Science and Technology; PoloniaFil: Adamek, L.. University of Toronto; CanadáFil: Adelman, J.. Northern Illinois University; Estados UnidosFil: Adersberger, M.. Ludwig-Maximilians-Universität München; AlemaniaFil: Adiguzel, A.. Bogazici University; TurquíaFil: Adorni,S.. Université de Genève; SuizaFil: Adye, T.. Universite Paris-Saclay;Fil: Affolder, A. A.. University of California Santa Cruz; Estados UnidosFil: Afik, Y.. Technion - Israel Institute of Technology; IsraelFil: Agapopoulou, C.. Universite Paris-Saclay;Fil: Agaras, M. N.. Université Clermont Auvergne; Francia. Centre National de la Recherche Scientifique; FranciaFil: Aggarwal, A.. Radboud Universiteit Nijmegen; Países BajosFil: Orellana, Gonzalo Enrique. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentin

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino