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Measurement of the tt¯Z and tt¯W cross sections in proton-proton collisions at s=13 TeV with the ATLAS detector

Physical Review D 2019年第7期99卷 072009-072009页

作者： M. Aaboud G. Aad B. Abbott D. C. Abbott O. Abdinov B. Abeloos D. K. Abhayasinghe S. H. Abidi O. S. AbouZeid N. L. Abraham H. Abramowicz H. Abreu Y. Abulaiti B. S. Acharya S. Adachi L. Adam L. Adamczyk L. Adamek J. Adelman M. Adersberger A. Adiguzel T. Adye A. A. Affolder Y. Afik C. Agheorghiesei J. A. Aguilar-Saavedra F. Ahmadov G. Aielli S. Akatsuka T. P. A. Åkesson E. Akilli A. V. Akimov G. L. Alberghi J. Albert P. Albicocco M. J. Alconada Verzini S. Alderweireldt M. Aleksa I. N. Aleksandrov C. Alexa D. Alexandre T. Alexopoulos M. Alhroob B. Ali G. Alimonti J. Alison S. P. Alkire C. Allaire B. M. M. Allbrooke B. W. Allen P. P. Allport A. Aloisio A. Alonso F. Alonso C. Alpigiani A. A. Alshehri M. I. Alstaty B. Alvarez Gonzalez D. Álvarez Piqueras M. G. Alviggi B. T. Amadio Y. Amaral Coutinho A. Ambler L. Ambroz C. Amelung D. Amidei S. P. Amor Dos Santos S. Amoroso C. S. Amrouche F. An C. Anastopoulos L. S. Ancu N. Andari T. Andeen C. F. Anders J. K. Anders K. J. Anderson A. Andreazza V. Andrei C. R. Anelli S. Angelidakis I. Angelozzi A. Angerami A. V. Anisenkov A. Annovi C. Antel M. T. Anthony M. Antonelli D. J. A. Antrim F. Anulli M. Aoki J. A. Aparisi Pozo L. Aperio Bella G. Arabidze J. P. Araque V. Araujo Ferraz R. Araujo Pereira A. T. H. Arce R. E. Ardell F. A. Arduh J-F. Arguin S. Argyropoulos J.-H. Arling A. J. Armbruster L. J. Armitage A. Armstrong O. Arnaez H. Arnold M. Arratia O. Arslan A. Artamonov G. Artoni S. Artz S. Asai N. Asbah E. M. Asimakopoulou L. Asquith K. Assamagan R. Astalos R. J. Atkin M. Atkinson N. B. Atlay K. Augsten G. Avolio R. Avramidou M. K. Ayoub A. M. Azoulay G. Azuelos A. E. Baas M. J. Baca H. Bachacou K. Bachas M. Backes P. Bagnaia M. Bahmani H. Bahrasemani A. J. Bailey V. R. Bailey J. T. Baines M. Bajic C. Bakalis O. K. Baker P. J. Bakker D. Bakshi Gupta S. Balaji E. M. Baldin P. Balek F. Balli W. K. Balunas J. Balz E. Banas A. Bandyopadhyay S. Banerjee A. A. E. Bannoura L. Barak W. M. Barbe E. L. Barberio D. Barberis M. Barbero T. Barillari M-S. Barisits J. Barkeloo T. Barklow Faculté des Sciences Université Mohamed Premier and LPTPM Oujda Morocco CPPM Aix-Marseille Université CNRS/IN2P3 Marseille France Homer L. Dodge Department of Physics and Astronomy University of Oklahoma Norman Oklahoma USA Department of Physics University of Massachusetts Amherst Massachusetts USA Institute of Physics Azerbaijan Academy of Sciences Baku Azerbaijan LAL Université Paris-Sud CNRS/IN2P3 Université Paris-Saclay Orsay France Department of Physics Royal Holloway University of London Egham United Kingdom Department of Physics University of Toronto Toronto Ontario Canada Niels Bohr Institute University of Copenhagen Copenhagen Denmark Department of Physics and Astronomy University of Sussex Brighton United Kingdom Raymond and Beverly Sackler School of Physics and Astronomy Tel Aviv University Tel Aviv Israel Department of Physics Technion Israel Institute of Technology Haifa Israel High Energy Physics Division Argonne National Laboratory Argonne Illinois USA INFN Gruppo Collegato di Udine Sezione di Trieste Udine Italy ICTP Trieste Italy International Center for Elementary Particle Physics and Department of Physics University of Tokyo Tokyo Japan Institut für Physik Universität Mainz Mainz Germany AGH University of Science and Technology Faculty of Physics and Applied Computer Science Krakow Poland Department of Physics Northern Illinois University DeKalb Illinois USA Fakultät für Physik Ludwig-Maximilians-Universität München München Germany Department of Physics Bogazici University Istanbul Turkey Particle Physics Department Rutherford Appleton Laboratory Didcot United Kingdom Santa Cruz Institute for Particle Physics University of California Santa Cruz Santa Cruz California USA Department of Physics Alexandru Ioan Cuza University of Iasi Iasi Romania Departamento de Física Teorica y del Cosmos Universidad de Granada Granada (Spain) Spain Laboratório de Instrumentação e Física Experimental de Partículas—LIP Portugal Joi

A measurement of the associated production of a top-quark pair (tt¯) with a vector boson (W, Z) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented, using 36.1 fb−1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. Events are selected in channels with two same- or opposite-sign leptons (electrons or muons), three leptons or four leptons, and each channel is further divided into multiple regions to maximize the sensitivity of the measurement. The tt¯Z and tt¯W production cross sections are simultaneously measured using a combined fit to all regions. The best-fit values of the production cross sections are σtt¯Z=0.95±0.08stat±0.10syst pb and σtt¯W=0.87±0.13stat±0.14syst pb in agreement with the Standard Model predictions. The measurement of the tt¯Z cross section is used to set constraints on effective field theory operators which modify the tt¯Z vertex.

关键词： Effective field theory W & Z bosons Top quark

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Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in pp collisions at s=13 TeV with the ATLAS detector

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Physical Review D 2019年第9期99卷 092004-092004页

作者： M. Aaboud G. Aad B. Abbott D. C. Abbott O. Abdinov B. Abeloos D. K. Abhayasinghe S. H. Abidi O. S. AbouZeid N. L. Abraham H. Abramowicz H. Abreu Y. Abulaiti B. S. Acharya S. Adachi L. Adam L. Adamczyk L. Adamek J. Adelman M. Adersberger A. Adiguzel T. Adye A. A. Affolder Y. Afik C. Agheorghiesei J. A. Aguilar-Saavedra F. Ahmadov G. Aielli S. Akatsuka T. P. A. Åkesson E. Akilli A. V. Akimov G. L. Alberghi J. Albert P. Albicocco M. J. Alconada Verzini S. Alderweireldt M. Aleksa I. N. Aleksandrov C. Alexa D. Alexandre T. Alexopoulos M. Alhroob B. Ali G. Alimonti J. Alison S. P. Alkire C. Allaire B. M. M. Allbrooke B. W. Allen P. P. Allport A. Aloisio A. Alonso F. Alonso C. Alpigiani A. A. Alshehri M. I. Alstaty B. Alvarez Gonzalez D. Álvarez Piqueras M. G. Alviggi B. T. Amadio Y. Amaral Coutinho A. Ambler L. Ambroz C. Amelung D. Amidei S. P. Amor Dos Santos S. Amoroso C. S. Amrouche F. An C. Anastopoulos L. S. Ancu N. Andari T. Andeen C. F. Anders J. K. Anders K. J. Anderson A. Andreazza V. Andrei C. R. Anelli S. Angelidakis I. Angelozzi A. Angerami A. V. Anisenkov A. Annovi C. Antel M. T. Anthony M. Antonelli D. J. A. Antrim F. Anulli M. Aoki J. A. Aparisi Pozo L. Aperio Bella G. Arabidze J. P. Araque V. Araujo Ferraz R. Araujo Pereira A. T. H. Arce R. E. Ardell F. A. Arduh J-F. Arguin S. Argyropoulos J.-H. Arling A. J. Armbruster L. J. Armitage A. Armstrong O. Arnaez H. Arnold M. Arratia O. Arslan A. Artamonov G. Artoni S. Artz S. Asai N. Asbah E. M. Asimakopoulou L. Asquith K. Assamagan R. Astalos R. J. Atkin M. Atkinson N. B. Atlay K. Augsten G. Avolio R. Avramidou M. K. Ayoub A. M. Azoulay G. Azuelos A. E. Baas M. J. Baca H. Bachacou K. Bachas M. Backes P. Bagnaia M. Bahmani H. Bahrasemani A. J. Bailey V. R. Bailey J. T. Baines M. Bajic C. Bakalis O. K. Baker P. J. Bakker D. Bakshi Gupta S. Balaji E. M. Baldin P. Balek F. Balli W. K. Balunas J. Balz E. Banas A. Bandyopadhyay S. Banerjee A. A. E. Bannoura L. Barak W. M. Barbe E. L. Barberio D. Barberis M. Barbero T. Barillari M-S. Barisits J. Barkeloo T. Barklow Faculté des Sciences Université Mohamed Premier and LPTPM Oujda Morocco CPPM Aix-Marseille Université CNRS/IN2P3 Marseille France Homer L. Dodge Department of Physics and Astronomy University of Oklahoma Norman Oklahoma USA Department of Physics University of Massachusetts Amherst Massachusetts USA Institute of Physics Azerbaijan Academy of Sciences Baku Azerbaijan LAL Université Paris-Sud CNRS/IN2P3 Université Paris-Saclay Orsay France Department of Physics Royal Holloway University of London Egham United Kingdom Department of Physics University of Toronto Toronto ON Canada Niels Bohr Institute University of Copenhagen Copenhagen Denmark Department of Physics and Astronomy University of Sussex Brighton United Kingdom Raymond and Beverly Sackler School of Physics and Astronomy Tel Aviv University Tel Aviv Israel Department of Physics Technion Israel Institute of Technology Haifa Israel High Energy Physics Division Argonne National Laboratory Argonne Illinois USA INFN Gruppo Collegato di Udine Sezione di Trieste Udine Italy ICTP Trieste Italy International Center for Elementary Particle Physics and Department of Physics University of Tokyo Tokyo Japan Institut für Physik Universität Mainz Mainz Germany AGH University of Science and Technology Faculty of Physics and Applied Computer Science Krakow Poland Department of Physics Northern Illinois University DeKalb Illinois USA Fakultät für Physik Ludwig-Maximilians-Universität München München Germany Department of Physics Bogazici University Istanbul Turkey Particle Physics Department Rutherford Appleton Laboratory Didcot United Kingdom Santa Cruz Institute for Particle Physics University of California Santa Cruz Santa Cruz California USA Department of Physics Alexandru Ioan Cuza University of Iasi Iasi Romania Departamento de Física Teorica y del Cosmos Universidad de Granada Granada (Spain) Spain Laboratório de Instrumentação e Física Experimental de Partículas—LIP Portugal Joint Ins

A search for new particles decaying into a pair of top quarks is performed using proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at a center-of-mass energy of s=13 TeV corresponding to an integrated luminosity of 36.1 fb−1. Events consistent with top-quark pair production and the fully hadronic decay mode of the top quarks are selected by requiring multiple high transverse momentum jets including those containing b-hadrons. Two analysis techniques, exploiting dedicated top-quark pair reconstruction in different kinematic regimes, are used to optimize the search sensitivity to new hypothetical particles over a wide mass range. The invariant mass distribution of the two reconstructed top-quark candidates is examined for resonant production of new particles with various spins and decay widths. No significant deviation from the Standard Model prediction is observed and limits are set on the production cross-section times branching fraction for new hypothetical Z′ bosons, dark-matter mediators, Kaluza-Klein gravitons and Kaluza-Klein gluons. By comparing with the predicted production cross sections, the Z′ boson in the topcolor-assisted-technicolor model is excluded for masses up to 3.1–3.6 TeV, the dark-matter mediators in a simplified framework are excluded in the mass ranges from 0.8 to 0.9 TeV and from 2.0 to 2.2 TeV, and the Kaluza-Klein gluon is excluded for masses up to 3.4 TeV, depending on the decay widths of the particles.

关键词： Gravitons Hypothetical gauge bosons Top quark Hadron colliders

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Search for heavy long-lived multicharged particles in proton-proton collisions at s=13 TeV using the ATLAS detector

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Physical Review D 2019年第5期99卷 052003-052003页

A search for heavy long-lived multicharged particles is performed using the ATLAS detector at the LHC. Data with an integrated luminosity of 36.1 fb−1 collected in 2015 and 2016 from proton-proton collisions at s=13 TeV are examined. Particles producing anomalously high ionization, consistent with long-lived massive particles with electric charges from |q|=2e to |q|=7e, are searched for. No events are observed, and 95% confidence level cross-section upper limits are interpreted as lower mass limits for a Drell-Yan production model. Multicharged particles with masses between 50 and 980–1220 GeV (depending on their electric charge) are excluded.

关键词： Extensions of fermion sector

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Search for long-lived particles produced in pp collisions at s=13 TeV that decay into displaced hadronic jets in the ATLAS muon spectrometer

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Physical Review D 2019年第5期99卷 052005-052005页

作者： M. Aaboud G. Aad B. Abbott O. Abdinov B. Abeloos D. K. Abhayasinghe S. H. Abidi O. S. AbouZeid N. L. Abraham H. Abramowicz H. Abreu Y. Abulaiti B. S. Acharya S. Adachi L. Adamczyk J. Adelman M. Adersberger A. Adiguzel T. Adye A. A. Affolder Y. Afik C. Agheorghiesei J. A. Aguilar-Saavedra F. Ahmadov G. Aielli S. Akatsuka T. P. A. Åkesson E. Akilli A. V. Akimov G. L. Alberghi J. Albert P. Albicocco M. J. Alconada Verzini S. Alderweireldt M. Aleksa I. N. Aleksandrov C. Alexa T. Alexopoulos M. Alhroob B. Ali G. Alimonti J. Alison S. P. Alkire C. Allaire B. M. M. Allbrooke B. W. Allen P. P. Allport A. Aloisio A. Alonso F. Alonso C. Alpigiani A. A. Alshehri M. I. Alstaty B. Alvarez Gonzalez D. Álvarez Piqueras M. G. Alviggi B. T. Amadio Y. Amaral Coutinho L. Ambroz C. Amelung D. Amidei S. P. Amor Dos Santos S. Amoroso C. S. Amrouche C. Anastopoulos L. S. Ancu N. Andari T. Andeen C. F. Anders J. K. Anders K. J. Anderson A. Andreazza V. Andrei C. R. Anelli S. Angelidakis I. Angelozzi A. Angerami A. V. Anisenkov A. Annovi C. Antel M. T. Anthony M. Antonelli D. J. A. Antrim F. Anulli M. Aoki J. A. Aparisi Pozo L. Aperio Bella G. Arabidze J. P. Araque V. Araujo Ferraz R. Araujo Pereira A. T. H. Arce R. E. Ardell F. A. Arduh J-F. Arguin S. Argyropoulos A. J. Armbruster L. J. Armitage A. Armstrong O. Arnaez H. Arnold M. Arratia O. Arslan A. Artamonov G. Artoni S. Artz S. Asai N. Asbah E. M. Asimakopoulou L. Asquith K. Assamagan R. Astalos R. J. Atkin M. Atkinson N. B. Atlay K. Augsten G. Avolio R. Avramidou M. K. Ayoub G. Azuelos A. E. Baas M. J. Baca H. Bachacou K. Bachas M. Backes P. Bagnaia M. Bahmani H. Bahrasemani A. J. Bailey J. T. Baines M. Bajic C. Bakalis O. K. Baker P. J. Bakker D. Bakshi Gupta S. Balaji E. M. Baldin P. Balek F. Balli W. K. Balunas J. Balz E. Banas A. Bandyopadhyay S. Banerjee A. A. E. Bannoura L. Barak W. M. Barbe E. L. Barberio D. Barberis M. Barbero T. Barillari M-S. Barisits J. Barkeloo T. Barklow R. Barnea S. L. Barnes B. M. Barnett R. M. Barnett Z. Barnovska-Blenessy A. Baroncelli G. Barone A. Faculté des Sciences Université Mohamed Premier and LPTPM Oujda Morocco CPPM Aix-Marseille Université CNRS/IN2P3 Marseille France Homer L. Dodge Department of Physics and Astronomy University of Oklahoma Norman Oklahoma USA Institute of Physics Azerbaijan Academy of Sciences Baku Azerbaijan LAL Université Paris-Sud CNRS/IN2P3 Université Paris-Saclay Orsay France Department of Physics Royal Holloway University of London Egham United Kingdom Department of Physics University of Toronto Toronto ON Canada Niels Bohr Institute University of Copenhagen Copenhagen Denmark Department of Physics and Astronomy University of Sussex Brighton United Kingdom Raymond and Beverly Sackler School of Physics and Astronomy Tel Aviv University Tel Aviv Israel Department of Physics Technion Israel Institute of Technology Haifa Israel High Energy Physics Division Argonne National Laboratory Argonne Illinois USA INFN Gruppo Collegato di Udine Sezione di Trieste Udine Italy ICTP Trieste Italy International Center for Elementary Particle Physics and Department of Physics University of Tokyo Tokyo Japan AGH University of Science and Technology Faculty of Physics and Applied Computer Science Krakow Poland Department of Physics Northern Illinois University DeKalb Illinois USA Fakultät für Physik Ludwig-Maximilians-Universität München München Germany Department of Physics Bogazici University Istanbul Turkey Particle Physics Department Rutherford Appleton Laboratory Didcot United Kingdom Santa Cruz Institute for Particle Physics University of California Santa Cruz Santa Cruz California USA Department of Physics Alexandru Ioan Cuza University of Iasi Iasi Romania Departamento de Física Teorica y del Cosmos Universidad de Granada Granada (Spain) Spain Laboratório de Instrumentação e Física Experimental de Partículas—LIP Portugal Joint Institute for Nuclear Research Dubna Russia INFN Sezione di Roma Tor Vergata Italy Dipartimento di Fisica Università di Roma Tor Verga

A search for the decay of neutral, weakly interacting, long-lived particles using data collected by the ATLAS detector at the LHC is presented. The analysis in this paper uses 36.1 fb−1 of proton-proton collision data at s=13 TeV recorded in 2015–2016. The search employs techniques for reconstructing vertices of long-lived particles decaying into jets in the muon spectrometer exploiting a two-vertex strategy and a novel technique that requires only one vertex in association with additional activity in the detector that improves the sensitivity for longer lifetimes. The observed numbers of events are consistent with the expected background and limits for several benchmark signals are determined.

关键词： Particle decays Supersymmetry

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Search for four-top-quark production in the single-lepton and opposite-sign dilepton final states in pp collisions at s=13 TeV with the ATLAS detector

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Physical Review D 2019年第5期99卷 052009-052009页

作者： M. Aaboud G. Aad B. Abbott O. Abdinov B. Abeloos D. K. Abhayasinghe S. H. Abidi O. S. AbouZeid N. L. Abraham H. Abramowicz H. Abreu Y. Abulaiti B. S. Acharya S. Adachi L. Adamczyk J. Adelman M. Adersberger A. Adiguzel T. Adye A. A. Affolder Y. Afik C. Agheorghiesei J. A. Aguilar-Saavedra F. Ahmadov G. Aielli S. Akatsuka T. P. A. Åkesson E. Akilli A. V. Akimov G. L. Alberghi J. Albert P. Albicocco M. J. Alconada Verzini S. Alderweireldt M. Aleksa I. N. Aleksandrov C. Alexa T. Alexopoulos M. Alhroob B. Ali G. Alimonti J. Alison S. P. Alkire C. Allaire B. M. M. Allbrooke B. W. Allen P. P. Allport A. Aloisio A. Alonso F. Alonso C. Alpigiani A. A. Alshehri M. I. Alstaty B. Alvarez Gonzalez D. Álvarez Piqueras M. G. Alviggi B. T. Amadio Y. Amaral Coutinho L. Ambroz C. Amelung D. Amidei S. P. Amor Dos Santos S. Amoroso C. S. Amrouche C. Anastopoulos L. S. Ancu N. Andari T. Andeen C. F. Anders J. K. Anders K. J. Anderson A. Andreazza V. Andrei C. R. Anelli S. Angelidakis I. Angelozzi A. Angerami A. V. Anisenkov A. Annovi C. Antel M. T. Anthony M. Antonelli D. J. A. Antrim F. Anulli M. Aoki J. A. Aparisi Pozo L. Aperio Bella G. Arabidze J. P. Araque V. Araujo Ferraz R. Araujo Pereira A. T. H. Arce R. E. Ardell F. A. Arduh J-F. Arguin S. Argyropoulos A. J. Armbruster L. J. Armitage A. Armstrong O. Arnaez H. Arnold M. Arratia O. Arslan A. Artamonov G. Artoni S. Artz S. Asai N. Asbah A. Ashkenazi E. M. Asimakopoulou L. Asquith K. Assamagan R. Astalos R. J. Atkin M. Atkinson N. B. Atlay K. Augsten G. Avolio R. Avramidou M. K. Ayoub G. Azuelos A. E. Baas M. J. Baca H. Bachacou K. Bachas M. Backes P. Bagnaia M. Bahmani H. Bahrasemani A. J. Bailey J. T. Baines M. Bajic C. Bakalis O. K. Baker P. J. Bakker D. Bakshi Gupta E. M. Baldin P. Balek F. Balli W. K. Balunas J. Balz E. Banas A. Bandyopadhyay S. Banerjee A. A. E. Bannoura L. Barak W. M. Barbe E. L. Barberio D. Barberis M. Barbero T. Barillari M-S. Barisits J. Barkeloo T. Barklow N. Barlow R. Barnea S. L. Barnes B. M. Barnett R. M. Barnett Z. Barnovska-Blenessy A. Baroncelli Faculté des Sciences Université Mohamed Premier and LPTPM Oujda Morocco CPPM Aix-Marseille Université CNRS/IN2P3 Marseille France Homer L. Dodge Department of Physics and Astronomy University of Oklahoma Norman Oklahoma USA Institute of Physics Azerbaijan Academy of Sciences Baku Azerbaijan LAL Université Paris-Sud CNRS/IN2P3 Université Paris-Saclay Orsay France Department of Physics Royal Holloway University of London Egham United Kingdom Department of Physics University of Toronto Toronto Ontario Canada Niels Bohr Institute University of Copenhagen Copenhagen Denmark Department of Physics and Astronomy University of Sussex Brighton United Kingdom Raymond and Beverly Sackler School of Physics and Astronomy Tel Aviv University Tel Aviv Israel Department of Physics Technion Israel Institute of Technology Haifa Israel High Energy Physics Division Argonne National Laboratory Argonne Illinois USA INFN Gruppo Collegato di Udine Sezione di Trieste Udine Italy ICTP Trieste Italy International Center for Elementary Particle Physics and Department of Physics University of Tokyo Tokyo Japan AGH University of Science and Technology Faculty of Physics and Applied Computer Science Krakow Poland Department of Physics Northern Illinois University DeKalb Illinois USA Fakultät für Physik Ludwig-Maximilians-Universität München München Germany Department of Physics Bogazici University Istanbul Turkey Particle Physics Department Rutherford Appleton Laboratory Didcot United Kingdom Santa Cruz Institute for Particle Physics University of California Santa Cruz Santa Cruz California USA Department of Physics Alexandru Ioan Cuza University of Iasi Iasi Romania Departamento de Física Teorica y del Cosmos Universidad de Granada Granada (Spain) Spain Laboratório de Instrumentação e Física Experimental de Partículas - LIP Portugal Joint Institute for Nuclear Research Dubna Russia INFN Sezione di Roma Tor Vergata Roma Italy Dipartimento di Fisica Università di

A search for four-top-quark production, tt¯tt¯, is presented. It is based on proton-proton collision data with a center-of-mass energy s=13 TeV collected by the ATLAS detector at the Large Hadron Collider during the years 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb−1. Data are analyzed in both the single-lepton and opposite-sign dilepton channels, characterized by the presence of one or two isolated electrons or muons with high-transverse momentum and multiple jets. A data-driven method is used to estimate the dominant background from top-quark pair production in association with jets. No significant excess above the Standard Model expectation is observed. The result is combined with the previous same-sign dilepton and multilepton searches carried out by the ATLAS Collaboration and an observed (expected) upper limit of 5.3 (2.1) times the four-top-quark Standard Model cross section is obtained at 95% confidence level. Additionally, an upper limit on the anomalous four-top-quark production cross section is set in the context of an effective field theory model.

关键词： Quantum chromodynamics Top quark Particle data analysis

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Search for pairs of highly collimated photon-jets in pp collisions at s=13 TeV with the ATLAS detector

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Physical Review D 2019年第1期99卷 012008-012008页

作者： M. Aaboud G. Aad B. Abbott O. Abdinov B. Abeloos D. K. Abhayasinghe S. H. Abidi O. S. AbouZeid N. L. Abraham H. Abramowicz H. Abreu Y. Abulaiti B. S. Acharya S. Adachi L. Adamczyk J. Adelman M. Adersberger A. Adiguzel T. Adye A. A. Affolder Y. Afik C. Agheorghiesei J. A. Aguilar-Saavedra F. Ahmadov G. Aielli S. Akatsuka T. P. A. Åkesson E. Akilli A. V. Akimov G. L. Alberghi J. Albert P. Albicocco M. J. Alconada Verzini S. Alderweireldt M. Aleksa I. N. Aleksandrov C. Alexa G. Alexander T. Alexopoulos M. Alhroob B. Ali G. Alimonti J. Alison S. P. Alkire C. Allaire B. M. M. Allbrooke B. W. Allen P. P. Allport A. Aloisio A. Alonso F. Alonso C. Alpigiani A. A. Alshehri M. I. Alstaty B. Alvarez Gonzalez D. Álvarez Piqueras M. G. Alviggi B. T. Amadio Y. Amaral Coutinho L. Ambroz C. Amelung D. Amidei S. P. Amor Dos Santos S. Amoroso C. S. Amrouche C. Anastopoulos L. S. Ancu N. Andari T. Andeen C. F. Anders J. K. Anders K. J. Anderson A. Andreazza V. Andrei C. R. Anelli S. Angelidakis I. Angelozzi A. Angerami A. V. Anisenkov A. Annovi C. Antel M. T. Anthony M. Antonelli D. J. A. Antrim F. Anulli M. Aoki L. Aperio Bella G. Arabidze Y. Arai J. P. Araque V. Araujo Ferraz R. Araujo Pereira A. T. H. Arce R. E. Ardell F. A. Arduh J-F. Arguin S. Argyropoulos A. J. Armbruster L. J. Armitage A. Armstrong O. Arnaez H. Arnold M. Arratia O. Arslan A. Artamonov G. Artoni S. Artz S. Asai N. Asbah A. Ashkenazi E. M. Asimakopoulou L. Asquith K. Assamagan R. Astalos R. J. Atkin M. Atkinson N. B. Atlay K. Augsten G. Avolio R. Avramidou B. Axen M. K. Ayoub G. Azuelos A. E. Baas M. J. Baca H. Bachacou K. Bachas M. Backes P. Bagnaia M. Bahmani H. Bahrasemani A. J. Bailey J. T. Baines M. Bajic C. Bakalis O. K. Baker P. J. Bakker D. Bakshi Gupta E. M. Baldin P. Balek F. Balli W. K. Balunas J. Balz E. Banas A. Bandyopadhyay S. Banerjee A. A. E. Bannoura L. Barak W. M. Barbe E. L. Barberio D. Barberis M. Barbero T. Barillari M-S. Barisits J. Barkeloo T. Barklow N. Barlow R. Barnea S. L. Barnes B. M. Barnett R. M. Barnett Z. Barnovska-Blenessy A. Faculté des Sciences Université Mohamed Premier and LPTPM Oujda Morocco CPPM Aix-Marseille Université CNRS/IN2P3 Marseille France Homer L. Dodge Department of Physics and Astronomy University of Oklahoma Norman Oklahoma USA Institute of Physics Azerbaijan Academy of Sciences Baku Azerbaijan LAL Université Paris-Sud CNRS/IN2P3 Université Paris-Saclay Orsay France Department of Physics Royal Holloway University of London Egham United Kingdom Department of Physics University of Toronto Toronto Ontario Canada Santa Cruz Institute for Particle Physics University of California Santa Cruz Santa Cruz California USA Department of Physics and Astronomy University of Sussex Brighton United Kingdom Raymond and Beverly Sackler School of Physics and Astronomy Tel Aviv University Tel Aviv Israel Department of Physics Technion Israel Institute of Technology Haifa Israel High Energy Physics Division Argonne National Laboratory Argonne Illinois USA INFN Gruppo Collegato di Udine Sezione di Trieste Udine Italy ICTP Trieste Italy International Center for Elementary Particle Physics and Department of Physics University of Tokyo Tokyo Japan AGH University of Science and Technology Faculty of Physics and Applied Computer Science Krakow Poland Department of Physics Northern Illinois University DeKalb Illinois USA Fakultät für Physik Ludwig-Maximilians-Universität München München Germany Department of Physics Bogazici University Istanbul Turkey Particle Physics Department Rutherford Appleton Laboratory Didcot United Kingdom Department of Physics Alexandru Ioan Cuza University of Iasi Iasi Romania Departamento de Física Teorica y del Cosmos Universidad de Granada Granada (Spain) Spain Laboratório de Instrumentação e Física Experimental de Partículas - LIP Portugal Joint Institute for Nuclear Research Dubna Russia INFN Sezione di Roma Tor Vergata Italy Dipartimento di Fisica Università di Roma Tor Vergata Roma Italy Faculty of Science Kyoto University Kyoto

Results of a search for the pair production of photon-jets—collimated groupings of photons—in the ATLAS detector at the Large Hadron Collider are reported. Highly collimated photon-jets can arise from the decay of new, highly boosted particles that can decay to multiple photons collimated enough to be identified in the electromagnetic calorimeter as a single, photonlike energy cluster. Data from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 36.7 fb−1, were collected in 2015 and 2016. Candidate photon-jet pair production events are selected from those containing two reconstructed photons using a set of identification criteria much less stringent than that typically used for the selection of photons, with additional criteria applied to provide improved sensitivity to photon-jets. Narrow excesses in the reconstructed diphoton mass spectra are searched for. The observed mass spectra are consistent with the Standard Model background expectation. The results are interpreted in the context of a model containing a new, high-mass scalar particle with narrow width, X, that decays into pairs of photon-jets via new, light particles, a. Upper limits are placed on the cross section times the product of branching ratios σ×B(X→aa)×B(a→γγ)2 for 200 GeV

关键词： Extensions of Higgs sector Hypothetical scalars Photons Hadron colliders

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Microscopic control of Si29 nuclear spins near phosphorus donors in silicon

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Physical Review B 2015年第12期92卷 121202(R)-121202(R)页

作者： J. Järvinen D. Zvezdov J. Ahokas S. Sheludyakov O. Vainio L. Lehtonen S. Vasiliev Y. Fujii S. Mitsudo T. Mizusaki M. Gwak SangGap Lee Soonchil Lee L. Vlasenko Wihuri Physical Laboratory Department of Physics and Astronomy University of Turku 20014 Turku Finland Institute of Physics Kazan Federal University Kazan 420008 Russia Research Center for Development of Far-Infrared Region University of Fukui 3-9-1 Bunkyo Fukui 910-8507 Japan Division of Materials Science Korea Basic Science Institute 169-148 Gwahak-ro Yuseong-gu Daejeon 305-806 Korea Department of Physics Korea Advanced Institute of Science and Technology 291 Daehak-ro Yuseong-gu Daejeon 305-701 Korea A. F. Ioffe Physico-Technical Institute Russian Academy of Sciences 194021 St. Petersburg Russia

We demonstrate an efficient control of Si29 nuclear spins for specific lattice sites near P31 donors in silicon at temperatures below 1 K and in a high magnetic field of 4.6 T. Excitation of the forbidden electron-nuclear transitions leads to a pattern of well-resolved holes and peaks in the electron spin resonance (ESR) lines of P31. The pattern originates from dynamic polarization (DNP) of the Si29 nuclear spins near the donors via the solid effect. DNP of Si29 is demonstrated also with the Overhauser effect where the allowed ESR transitions are excited. In this case mostly the remote Si29 nuclei having weak interaction with the donors are polarized, which results in a single hole and a sharp peak pair in the ESR spectrum. Our work shows that the solid effect can be used for initialization of Si29 nuclear spin qubits near the donors.

关键词： POLARIZATION (Nuclear physics) DIFFUSION control MAGNETIC field effects THERMAL properties of phosphorus ELECTRIC properties of silicon

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Plasmonic superfocusing of THz waves in metallic V-groove tapered waveguide theoretically considered by quasi-separation of variables

Plasmonic superfocusing of THz waves in metallic V-groove ta...

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International Conference on infrared and Millimeter Waves

作者： Kazuyoshi Kurihara Fumiyoshi Kuwashima Osamu Morikawa Kohji Yamamoto Masahiko Tani Department of Physics Faculty of Education and Regional Studies University of Fukui Fukui Japan Department of Electrical Electronics and Comnuter Engineering Fukui University of Technology Fukui Japan Japan Coast Guard Academy Hiroshima Japan Research Center for Development of Far-Infrared Region University of Fukui Fukui Japan

A non-adiabatic superfocusing theory of THz waves in a metallic V-groove tapered waveguide is studied by quasi-separation of variables for the explanation of our recent experimental results (Appl. Phys. Express, vol. 7, 112401, 2014). Approximate analytical solutions are obtained for the two regions at the apex and in the vicinity of it, where as the result the property of plasmonic superfocusing is analytically discussable in details.

关键词： Optical waveguides Plasmons Surface waves Optical surface waves Optical diffraction Waveguide theory

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High effective generation and detection of THz waves using a laser chaos and a super-focusing with metal V-grooved waveguides

High effective generation and detection of THz waves using a...

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International Conference on infrared and Millimeter Waves

作者： Fumiyoshi Kuwashima Takuya Shirao Toshihiro Kishibata Yusuke Akamine Noriyuki Iwao Manatu Ooi Masahiko Tani Kazuyoshi Kurihara Kohji Yamamoto Takeshi Nagashima Makoto Nakajima Masanori Hangyo Department of Electrical Electronics and Computer Engineering Fukui University of Technology Fukui Japan Research Center for Development of Far-Infrared Region University of Fukui Fukui Japan Faculty of Education and Regional Studies University of Fukui Fukui Japan Setsunan University Neyagawa City Osaka Japan Institute of Laser Engineering Osaka University Osaka Japan

Generation of a wide-range THz waves are investigated from a photoconductive antenna excited using a chaotic oscillation multimode semiconductor laser with optical delayed feedback by an external mirror. The properties of the generated THz wave are compared with those of a case excited by a CW steady state laser. The stable THz wave is obtained from the multimode-laser diode excited photoconductive antenna by using a laser chaos. For a high sensitive detection, a metal V-grooved waveguide (MVG) is also used. The 1.6 times signal is detected using MVG compared with conventional system using Si lens.

关键词： Chaos Lenses Metals Optical waveguides Oscillators Mirrors Antennas

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Fast Microwave-assisted Pretreatment for Bioconversion of Sawdust Lignocellulose to Glucose

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Journal of Physics: Conference Series 2017年第1期846卷

作者： I Nyoman Sudiana Seitaro Mitsudo Prima Endang Susilowati Desak Ketut Sutiari Made Widana Arsana Muhammad Zamrun Firihu La Ode Ngkoimani La Aba Erzam Sahaluddin Hasan Edi Cahyono Svilen Sabchevski Haji Aripin Komang Gde Suastika Department of Physics Faculty of Mathematic and Natural Science Halu Oleo University Kampus Bumi Tridharma AnduonohuKendari 93232Indonesia Research Center for Development of Far-Infrared Region University of Fukui3-9-1 Bunkyo Fukui-shi 910-8507Japan Department of Chemistry Faculty of Mathematic and Natural Science Halu Oleo University Kampus Bumi Tridharma AnduonohuKendari 93232Indonesia Department of Agrotechnology Faculty of Agriculture Halu Oleo University Kampus Bumi Tridharma AnduonohuKendari 93232Indonesia Department of Geophysics Faculty of Earth Sciences and Technology Halu Oleo University Kampus Bumi Tridharma AnduonohuKendari 93232Indonesia Department of Mathematics Faculty of Mathematic and Natural Science Halu Oleo University Kampus Bumi Tridharma AnduonohuKendari 93232Indonesia Lab. Plasma Physics and Engineering Institute of Electronics of Bulgarian Academy of SciencesBulgaria Center for Material Processing and Renewable Energy Faculty of Learning Teacher and Education Science Siliwangi UniversityJl. Siliwangi 24 Tasikmalaya 46115 West JavaIndonesia Department of Physics Education Palangka Raya University73112Indonesia

A preliminary study of application microwave energy for bioconversion of cellulosic sawdust to glucose was performed. The effects of the microwave were compared to those of the conventional method for each solvent. It was expected that a broader mechanism responsible for the microwave effects on the chemical processes, especially the pretreatment on the hydrolysis of cellulose can be explained. Reagents used were an acid (HCl), an alkali (NaOH), and distilled water (H2O). The experimental results showed that the microwave-assisted pretreatment on the lignocellulosic sawdust faster than by using conventional heating (hotplate). Moreover by using microwave a higher glucose content compared to the conventional method was found. With microwave during hydrolisis, high temperatures and high reagent concentrations were not required. Pretreatment with a microwave at 800 Watt and solvent NaOH 22,50 mg/mL at a temperature of 120°c appeared to be most efficient found in this experiment. These results indicate that microwave effective for bioconversion of cellulosic sawdust to glucose. The microstructure evaluation by using SEM and XRD should be performed to understand more detail the effect especially on their cellulosic structural evolution.

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