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Measurement of exclusive Υ photoproduction from protons in p Pb collisions at s NN = 5.02 TeV. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2019; 79:277. [PMID: 31007586 PMCID: PMC6438325 DOI: 10.1140/epjc/s10052-019-6774-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 03/12/2019] [Indexed: 06/09/2023]
Abstract
The exclusive photoproduction of Υ ( nS ) meson states from protons, γ p → Υ ( nS ) p (with n = 1 , 2 , 3 ), is studied in ultraperipheral p Pb collisions at a centre-of-mass energy per nucleon pair ofs NN = 5.02 TeV . The measurement is performed using the Υ ( nS ) → μ + μ - decay mode, with data collected by the CMS experiment corresponding to an integrated luminosity of 32.6nb - 1 . Differential cross sections as functions of the Υ ( nS ) transverse momentum squared p T 2 , and rapidity y, are presented. The Υ ( 1 S ) photoproduction cross section is extracted in the rapidity range | y | < 2.2 , which corresponds to photon-proton centre-of-mass energies in the range 91 < W γ p < 826 GeV . The data are compared to theoretical predictions based on perturbative quantum chromodynamics and to previous measurements.
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Grants
- Austrian Federal Ministry of Education, Science and Research and Economy
- Austrian Science Fund
- Belgian Fonds de la Recherche Scientifique
- Belgian Fonds voor Wetenschappelijk Onderzoek
- CNPq
- CAPES
- FAPERGS
- FAPERJ
- FAPESP
- Bulgarian Ministry of Education and Science
- CERN
- Chinese Academy of Sciences
- Ministry of Science and Technology
- Chinese National Natural Science Foundation of China
- Colombian Funding Agency (COLCIENCIAS)
- Croatian Ministry of Science, Education and Sport
- Croatian Science Foundation
- Research Promotion Foundation
- SENESCYT
- Ministry of Education and Research
- Estonian Research Council via IUT23-4 and IUT23-6
- European Regional Development Fund
- Academy of Finland
- Finnish Ministry of Education and Culture
- Helsinki Institute of Physics
- Institut National de Physique NuclTaire et de Physique des Particules
- Centre National de la Recherche Scientifique
- Commissariat a l’+nergie Atomique et aux +nergies Alternatives
- Bundesministerium fnr Bildung und Forschung
- Deutsche Forschungsgemeinschaft
- Helmholtz-Gemeinschaft Deutscher Forschungszentren
- General Secretariat for Research and Technology
- National Scientific Research Foundation
- National Innovation Office
- Department of Atomic Energy
- Department of Science and Technology
- Institute for Research in Fundamental Studies
- Science Foundation
- Istituto Nazionale di Fisica Nucleare
- Korean Ministry of Education, Science and Technology
- National Research Foundation of Korea (NRF)
- MES
- Lithuanian Academy of Sciences
- Ministry of Education
- University of Malaya
- BUAP
- CINVESTAV
- CONACYT
- LNS
- SEP
- UASLP
- MOS
- Ministry of Business, Innovation and Employment
- Pakistan Atomic Energy Commission
- Ministry of Science and Higher Education
- National Science Centre
- Fundatpo para a CiOncia e a Tecnologia
- JINR, Dubna
- Ministry of Education and Science of the Russian Federation
- Federal Agency of Atomic Energy of the Russian Federation
- Russian Academy of Sciences
- National Research Center “Kurchatov Institute”
- Russian Competitiveness Program of National Research Nuclear University/ Moscow Engineering Physics Institute
- Ministry of Education, Science and Technological Development of Serbia
- Secretaría de Estado de Investigación, Desarrollo e Innovación
- Programa Consolider-Ingenio 2010
- Plan de Ciencia, Tecnología e Innovación 2013-2017 del Principado de Asturias
- Fondo Europeo de Desarrollo Regional, Spain
- MOSTR
- ETH Board
- ETH Zurich
- PSI
- SNF
- UniZH
- Canton Zurich
- SER
- Ministry of Science and Technology
- Thailand Center of Excellence in Physics
- Institute for the Promotion of Teaching Science and Technology of Thailand
- Special Task Force for Activating Research
- National Science and Technology Development Agency of Thailand
- Scientific and Technical Research Council of Turkey
- Turkish Atomic Energy Authority
- National Academy of Sciences of Ukraine
- State Fund for Fundamental Researches
- Science and Technology Facilities Council
- US Department of Energy
- US National Science Foundation
- Marie-Curie programme
- European Research Council and EPLANET (European Union)
- Horizon 2020 Grant, contract No. 675440 (European Union)
- Leventis Foundation
- Alfred P. Sloan Foundation
- Alexander von Humboldt Foundation
- Belgian Federal Science Policy Office
- Fonds pour la Formation a la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium)
- Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium)
- Belgian Fonds de la Recherche Scientifique, “Excellence of Science - EOS” - be.h project n. 30820817
- Belgian Fonds voor Wetenschappelijk Onderzoek, “Excellence of Science - EOS” - be.h project n. 30820817
- Ministry of Education, Youth and Sports (MEYS) of the Czech Republic
- Lendúlet (“Momentum”) Programme and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences
- New National Excellence Program ÚNKP, the NKFIA research Grants 123842, 123959, 124845, 124850 and 125105
- Council of Science and Industrial Research, India
- HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund
- National Science Center, contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406
- National Priorities Research Program by Qatar National Research Fund
- Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, Grant MDM-2015-0509
- Programa Severo Ochoa del Principado de Asturias
- Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF
- Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand)
- CUAASC
- Welch Foundation, contract C-1845
- Weston Havens Foundation
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Observation of Medium-Induced Modifications of Jet Fragmentation in Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV Using Isolated Photon-Tagged Jets. PHYSICAL REVIEW LETTERS 2018; 121:242301. [PMID: 30608764 DOI: 10.1103/physrevlett.121.242301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 10/16/2018] [Indexed: 06/09/2023]
Abstract
Measurements of fragmentation functions for jets associated with an isolated photon are presented for the first time in pp and Pb-Pb collisions. The analysis uses data collected with the CMS detector at the CERN LHC at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Fragmentation functions are obtained for jets with p_{T}^{jet}>30 GeV/c in events containing an isolated photon with p_{T}^{γ}>60 GeV/c, using charged tracks with transverse momentum p_{T}^{trk}>1 GeV/c in a cone around the jet axis. The association with an isolated photon constrains the initial p_{T} and azimuthal angle of the parton whose shower produced the jet. For central Pb-Pb collisions, modifications of the jet fragmentation functions are observed when compared to those measured in pp collisions, while no significant differences are found in the 50% most peripheral collisions. Jets in central Pb-Pb events show an excess (depletion) of low (high) p_{T} particles, with a transition around 3 GeV/c. This measurement shows for the first time the in-medium shower modifications of partons (quark dominated) with well-defined initial kinematics. It constitutes a new well-controlled reference for testing theoretical models of the parton passage through the quark-gluon plasma.
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Measurement of differential cross sections for Z boson production in association with jets in proton-proton collisions at s = 13 TeV. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2018; 78:965. [PMID: 30881214 PMCID: PMC6394299 DOI: 10.1140/epjc/s10052-018-6373-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 10/29/2018] [Indexed: 05/31/2023]
Abstract
The production of a Z boson, decaying to two charged leptons, in association with jets in proton-proton collisions at a centre-of-mass energy of 13TeV is measured. Data recorded with the CMS detector at the LHC are used that correspond to an integrated luminosity of 2.19fb -1 . The cross section is measured as a function of the jet multiplicity and its dependence on the transverse momentum of the Z boson, the jet kinematic variables (transverse momentum and rapidity), the scalar sum of the jet momenta, which quantifies the hadronic activity, and the balance in transverse momentum between the reconstructed jet recoil and the Z boson. The measurements are compared with predictions from four different calculations. The first two merge matrix elements with different parton multiplicities in the final state and parton showering, one of which includes one-loop corrections. The third is a fixed-order calculation with next-to-next-to-leading order accuracy for the process with a Z boson and one parton in the final state. The fourth combines the fully differential next-to-next-to-leading order calculation of the process with no parton in the final state with next-to-next-to-leading logarithm resummation and parton showering.
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Grants
- Austrian Federal Ministry of Science, Research and Economy
- Austrian Science Fund
- Belgian Fonds de la Recherche Scientifique
- Belgian Fonds voor Wetenschappelijk Onderzoek
- CNPq
- CAPES
- FAPERJ
- FAPESP
- Bulgarian Ministry of Education and Science
- CERN
- Chinese Academy of Sciences
- Ministry of Science and Technology
- Chinese National Natural Science Foundation of China
- Colombian Funding Agency (COLCIENCIAS)
- Croatian Ministry of Science, Education and Sport
- Croatian Science Foundation
- Research Promotion Foundation
- SENESCYT
- Ministry of Education and Research
- Estonian Research Council via IUT23-4 and IUT23-6
- European Regional Development Fund
- Academy of Finland
- Finnish Ministry of Education and Culture
- Helsinki Institute of Physics
- Institut National de Physique NuclTaire et de Physique des Particules
- Centre National de la Recherche Scientifique
- Commissariat a l’+nergie Atomique et aux +nergies Alternatives
- Bundesministerium fnr Bildung und Forschung
- Deutsche Forschungsgemeinschaft
- Helmholtz-Gemeinschaft Deutscher Forschungszentren
- General Secretariat for Research and Technology
- National Scientific Research Foundation
- National Innovation Office
- Department of Atomic Energy
- Department of Science and Technology
- Institute for Research in Fundamental Studies
- Science Foundation
- Istituto Nazionale di Fisica Nucleare
- Korean Ministry of Education, Science and Technology
- National Research Foundation of Korea (NRF)
- Lithuanian Academy of Sciences
- Ministry of Education
- University of Malaya
- BUAP
- CINVESTAV
- CONACYT
- LNS
- SEP
- UASLP
- Ministry of Business, Innovation and Employment
- Pakistan Atomic Energy Commission
- Ministry of Science and Higher Education
- National Science Centre
- Fundatpo para a CiOncia e a Tecnologia
- JINR, Dubna
- Ministry of Education and Science of the Russian Federation
- Federal Agency of Atomic Energy of the Russian Federation
- Russian Academy of Sciences
- Russian Foundation for Basic Research
- Ministry of Education, Science and Technological Development of Serbia
- Secretaría de Estado de Investigación, Desarrollo e Innovación
- Programa Consolider-Ingenio 2010
- Plan de Ciencia, Tecnología e Innovación 2013-2017 del Principado de Asturias
- Fondo Europeo de Desarrollo Regional, Spain
- ETH Board
- ETH Zurich
- PSI
- SNF
- UniZH
- Canton Zurich
- SER
- Ministry of Science and Technology
- Thailand Center of Excellence in Physics
- Institute for the Promotion of Teaching Science and Technology of Thailand
- Special Task Force for Activating Research
- National Science and Technology Development Agency of Thailand
- Scientific and Technical Research Council of Turkey
- Turkish Atomic Energy Authority
- National Academy of Sciences of Ukraine
- State Fund for Fundamental Researches
- Science and Technology Facilities Council
- US Department of Energy
- US National Science Foundation
- Marie-Curie programme
- European Research Council and EPLANET (European Union)
- Horizon 2020 Grant, contract No. 675440 (European Union)
- Leventis Foundation
- Alfred P. Sloan Foundation
- Alexander von Humboldt Foundation
- Belgian Federal Science Policy Office
- Fonds pour la Formation a la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium)
- Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium)
- Belgian Fonds de la Recherche Scientifique, “Excellence of Science - EOS” - be.h project n. 30820817
- Belgian Fonds voor Wetenschappelijk Onderzoek, “Excellence of Science - EOS” - be.h project n. 30820817
- Ministry of Education, Youth and Sports (MEYS) of the Czech Republic
- Lendúlet (“Momentum”) Programme and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences
- New National Excellence Program ÚNKP, the NKFIA research grants 123842, 123959, 124845, 124850 and 125105
- Council of Science and Industrial Research, India
- HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund
- National Science Center, contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406
- National Priorities Research Program by Qatar National Research Fund
- Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509
- Programa Severo Ochoa del Principado de Asturias
- Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF
- Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand)
- CUAASC
- Welch Foundation, contract C-1845
- Weston Havens Foundation
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Measurement of the top quark mass with lepton+jets final states using p p collisions at s = 13 TeV. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2018; 78:891. [PMID: 30881206 PMCID: PMC6394251 DOI: 10.1140/epjc/s10052-018-6332-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 10/11/2018] [Indexed: 06/09/2023]
Abstract
The mass of the top quark is measured using a sample of t t ¯ events collected by the CMS detector using proton-proton collisions ats = 13 TeV at the CERN LHC. Events are selected with one isolated muon or electron and at least four jets from data corresponding to an integrated luminosity of 35.9fb - 1 . For each event the mass is reconstructed from a kinematic fit of the decay products to a t t ¯ hypothesis. Using the ideogram method, the top quark mass is determined simultaneously with an overall jet energy scale factor (JSF), constrained by the mass of the W boson in q q ¯ ' decays. The measurement is calibrated on samples simulated at next-to-leading order matched to a leading-order parton shower. The top quark mass is found to be 172.25 ± 0.08 (stat+JSF) ± 0.62 (syst) GeV . The dependence of this result on the kinematic properties of the event is studied and compared to predictions of different models of t t ¯ production, and no indications of a bias in the measurements are observed.
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Grants
- Austrian Federal Ministry of Education, Science and Research and Economy
- Austrian Science Fund
- Belgian Fonds de la Recherche Scientifique
- Belgian Fonds voor Wetenschappelijk Onderzoek
- CNPq
- CAPES
- FAPERGS
- FAPERJ
- FAPESP
- Bulgarian Ministry of Education and Science
- CERN
- Chinese Academy of Sciences
- Ministry of Science and Technology
- Chinese National Natural Science Foundation of China
- Colombian Funding Agency (COLCIENCIAS)
- Croatian Ministry of Science, Education and Sport
- Croatian Science Foundation
- Research Promotion Foundation
- SENESCYT
- Ministry of Education and Research
- Estonian Research Council via IUT23-4 and IUT23-6
- European Regional Development Fund
- Academy of Finland
- Finnish Ministry of Education and Culture
- Helsinki Institute of Physics
- Institut National de Physique NuclTaire et de Physique des Particules
- Centre National de la Recherche Scientifique
- Commissariat a l’+nergie Atomique et aux +nergies Alternatives
- Bundesministerium fnr Bildung und Forschung
- Deutsche Forschungsgemeinschaft
- Helmholtz-Gemeinschaft Deutscher Forschungszentren
- General Secretariat for Research and Technology
- National Scientific Research Foundation
- National Innovation Office
- Department of Atomic Energy
- Department of Science and Technology
- Institute for Research in Fundamental Studies
- Science Foundation
- Istituto Nazionale di Fisica Nucleare
- Korean Ministry of Education, Science and Technology
- National Research Foundation of Korea (NRF)
- MES
- Lithuanian Academy of Sciences
- Ministry of Education
- University of Malaya
- BUAP
- CINVESTAV
- CONACYT
- LNS
- SEP
- UASLP
- MOS
- Ministry of Business, Innovation and Employment
- Pakistan Atomic Energy Commission
- Ministry of Science and Higher Education
- National Science Centre
- Fundatpo para a CiOncia e a Tecnologia
- JINR, Dubna
- Ministry of Education and Science of the Russian Federation
- Federal Agency of Atomic Energy of the Russian Federation
- Russian Academy of Sciences
- National Research Center “Kurchatov Institute”
- Russian Competitiveness Program of National Research Nuclear University/ Moscow Engineering Physics Institute
- Ministry of Education, Science and Technological Development of Serbia
- Secretaría de Estado de Investigación, Desarrollo e Innovación
- Programa Consolider-Ingenio 2010
- Plan de Ciencia, Tecnología e Innovación 2013-2017 del Principado de Asturias
- Fondo Europeo de Desarrollo Regional, Spain
- MOSTR
- ETH Board
- ETH Zurich
- PSI
- SNF
- UniZH
- Canton Zurich
- SER
- Ministry of Science and Technology
- Thailand Center of Excellence in Physics
- Institute for the Promotion of Teaching Science and Technology of Thailand
- Special Task Force for Activating Research
- National Science and Technology Development Agency of Thailand
- Scientific and Technical Research Council of Turkey
- Turkish Atomic Energy Authority
- National Academy of Sciences of Ukraine
- State Fund for Fundamental Researches
- Science and Technology Facilities Council
- US Department of Energy
- US National Science Foundation
- Marie-Curie programme
- European Research Council and EPLANET (European Union)
- Horizon 2020 Grant, contract No. 675440 (European Union)
- Leventis Foundation
- Alfred P. Sloan Foundation
- Alexander von Humboldt Foundation
- Belgian Federal Science Policy Office
- Fonds pour la Formation a la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium)
- Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium)
- Belgian Fonds de la Recherche Scientifique, “Excellence of Science - EOS” - be.h project n. 30820817
- Belgian Fonds voor Wetenschappelijk Onderzoek, “Excellence of Science - EOS” - be.h project n. 30820817
- Ministry of Education, Youth and Sports (MEYS) of the Czech Republic
- Lendúlet (“Momentum”) Programme and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences
- New National Excellence Program ÚNKP, the NKFIA research grants 123842, 123959, 124845, 124850 and 125105
- Council of Science and Industrial Research, India
- HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund
- National Science Center, contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406
- National Priorities Research Program by Qatar National Research Fund
- Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509
- Programa Severo Ochoa del Principado de Asturias
- Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF
- Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand)
- CUAASC
- Welch Foundation, contract C-1845
- Weston Havens Foundation
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Search for new physics in dijet angular distributions using proton-proton collisions at s = 13 TeV and constraints on dark matter and other models. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2018; 78:789. [PMID: 30956565 PMCID: PMC6413623 DOI: 10.1140/epjc/s10052-018-6242-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 09/13/2018] [Indexed: 06/09/2023]
Abstract
A search is presented for physics beyond the standard model, based on measurements of dijet angular distributions in proton-proton collisions ats = 13 TeV . The data collected with the CMS detector at the LHC correspond to an integrated luminosity of 35.9fb - 1 . The observed distributions, corrected to particle level, are found to be in agreement with predictions from perturbative quantum chromodynamics that include electroweak corrections. Constraints are placed on models containing quark contact interactions, extra spatial dimensions, quantum black holes, or dark matter, using the detector-level distributions. In a benchmark model where only left-handed quarks participate, contact interactions are excluded at the 95% confidence level up to a scale of 12.8 or 17.5TeV, for destructive or constructive interference, respectively. The most stringent lower limits to date are set on the ultraviolet cutoff in the Arkani-Hamed-Dimopoulos-Dvali model of extra dimensions. In the Giudice-Rattazzi-Wells convention, the cutoff scale is excluded up to 10.1TeV. The production of quantum black holes is excluded for masses below 5.9 and 8.2TeV, depending on the model. For the first time, lower limits between 2.0 and 4.6TeVare set on the mass of a dark matter mediator for (axial-)vector mediators, for the universal quark couplingg q = 1.0 .
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Grants
- Austrian Federal Ministry of Science, Research and Economy
- Austrian Science Fund
- Belgian Fonds de la Recherche Scientifique
- Belgian Fonds voor Wetenschappelijk Onderzoek
- CNPq
- CAPES
- FAPERJ
- FAPESP
- Bulgarian Ministry of Education and Science
- CERN
- Chinese Academy of Sciences
- Ministry of Science and Technology
- Chinese National Natural Science Foundation of China
- Colombian Funding Agency (COLCIENCIAS)
- Croatian Ministry of Science, Education and Sport
- Croatian Science Foundation
- Research Promotion Foundation
- SENESCYT
- Ministry of Education and Research
- Estonian Research Council via IUT23-4 and IUT23-6
- European Regional Development Fund
- Academy of Finland
- Finnish Ministry of Education and Culture
- Helsinki Institute of Physics
- Institut National de Physique NuclTaire et de Physique des Particules
- Centre National de la Recherche Scientifique
- Commissariat a l’+nergie Atomique et aux +nergies Alternatives
- Bundesministerium fnr Bildung und Forschung
- Deutsche Forschungsgemeinschaft
- Helmholtz-Gemeinschaft Deutscher Forschungszentren
- General Secretariat for Research and Technology
- National Scientific Research Foundation
- National Innovation Office
- Department of Atomic Energy
- Department of Science and Technology
- Institute for Research in Fundamental Studies
- Science Foundation
- Istituto Nazionale di Fisica Nucleare
- Korean Ministry of Education, Science and Technology
- National Research Foundation of Korea (NRF)
- Lithuanian Academy of Sciences
- Ministry of Education
- University of Malaya
- BUAP
- CINVESTAV
- CONACYT
- LNS
- SEP
- UASLP
- Ministry of Business, Innovation and Employment
- Pakistan Atomic Energy Commission
- Ministry of Science and Higher Education
- National Science Centre
- Fundatpo para a CiOncia e a Tecnologia
- JINR, Dubna
- Ministry of Education and Science of the Russian Federation
- Federal Agency of Atomic Energy of the Russian Federation
- Russian Academy of Sciences
- Russian Foundation for Basic Research
- Russian Competitiveness Program of National Research Nuclear University/ Moscow Engineering Physics Institute
- Ministry of Education, Science and Technological Development of Serbia
- Secretaría de Estado de Investigación, Desarrollo e Innovación
- Programa Consolider-Ingenio 2010
- Plan de Ciencia, Tecnología e Innovación 2013-2017 del Principado de Asturias
- Fondo Europeo de Desarrollo Regional, Spain
- ETH Board
- ETH Zurich
- PSI
- SNF
- UniZH
- Canton Zurich
- SER
- Ministry of Science and Technology
- Thailand Center of Excellence in Physics
- Institute for the Promotion of Teaching Science and Technology of Thailand
- Special Task Force for Activating Research
- National Science and Technology Development Agency of Thailand
- Scientific and Technical Research Council of Turkey
- Turkish Atomic Energy Authority
- National Academy of Sciences of Ukraine
- State Fund for Fundamental Researches
- Science and Technology Facilities Council
- US Department of Energy
- US National Science Foundation
- Marie-Curie programme
- European Research Council and EPLANET (European Union)
- Horizon 2020 Grant, contract No. 675440 (European Union)
- Leventis Foundation
- Alfred P. Sloan Foundation
- Alexander von Humboldt Foundation
- Belgian Federal Science Policy Office
- Fonds pour la Formation a la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium)
- Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium)
- Belgian Fonds de la Recherche Scientifique, “Excellence of Science - EOS” - be.h project n. 30820817
- Belgian Fonds voor Wetenschappelijk Onderzoek, “Excellence of Science - EOS” - be.h project n. 30820817
- Ministry of Education, Youth and Sports (MEYS) of the Czech Republic
- Lendúlet (“Momentum”) Programme and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences
- New National Excellence Program ÚNKP, the NKFIA research grants 123842, 123959, 124845, 124850 and 125105
- Council of Science and Industrial Research, India
- HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund
- National Science Center, contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406
- National Priorities Research Program by Qatar National Research Fund
- Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509
- Programa Severo Ochoa del Principado de Asturias
- Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF
- Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand)
- CUAASC
- Welch Foundation, contract C-1845
- Weston Havens Foundation
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6
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Measurement of the Z / γ ∗ → τ τ cross section in pp collisions at s = 13 TeV and validation of τ lepton analysis techniques. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2018; 78:708. [PMID: 30956559 PMCID: PMC6413676 DOI: 10.1140/epjc/s10052-018-6146-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 08/10/2018] [Indexed: 06/09/2023]
Abstract
A measurement is presented of the Z / γ ∗ → τ τ cross section in pp collisions ats = 13 TeV , using data recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 2.3 fb - 1 . The product of the inclusive cross section and branching fraction is measured to be σ ( pp → Z / γ ∗ +X ) B ( Z / γ ∗ → τ τ ) = 1848 ± 12 ( stat ) ± 67 (syst \,+\,lumi) pb , in agreement with the standard model expectation, computed at next-to-next-to-leading order accuracy in perturbative quantum chromodynamics. The measurement is used to validate new analysis techniques relevant for future measurements of τ lepton production. The measurement also provides the reconstruction efficiency and energy scale for τ decays to hadrons+ ν τ final states, determined with respective relative uncertainties of 2.2 and 0.9%.
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Grants
- Austrian Federal Ministry of Science, Research and Economy
- Austrian Science Fund
- Belgian Fonds de la Recherche Scientifique
- Belgian Fonds voor Wetenschappelijk Onderzoek
- CNPq
- CAPES
- FAPERJ
- FAPERGS
- FAPESP
- Bulgarian Ministry of Education and Science
- CERN
- Chinese Academy of Sciences
- Ministry of Science and Technology
- Chinese National Natural Science Foundation of China
- Colombian Funding Agency (COLCIENCIAS)
- Croatian Ministry of Science, Education and Sport
- Croatian Science Foundation
- Research Promotion Foundation
- SENESCYT
- Ministry of Education and Research
- Estonian Research Council via IUT23-4 and IUT23-6
- European Regional Development Fund
- Academy of Finland
- Finnish Ministry of Education and Culture
- Helsinki Institute of Physics
- Institut National de Physique NuclTaire et de Physique des Particules
- Centre National de la Recherche Scientifique
- Commissariat a l’+nergie Atomique et aux +nergies Alternatives
- Bundesministerium fnr Bildung und Forschung
- Deutsche Forschungsgemeinschaft
- Helmholtz-Gemeinschaft Deutscher Forschungszentren
- General Secretariat for Research and Technology
- National Scientific Research Foundation
- National Innovation Office
- Department of Atomic Energy
- Department of Science and Technology
- Institute for Research in Fundamental Studies
- Science Foundation
- Istituto Nazionale di Fisica Nucleare
- Korean Ministry of Education, Science and Technology
- National Research Foundation of Korea (NRF)
- MES
- Lithuanian Academy of Sciences
- Ministry of Education
- University of Malaya
- BUAP
- CINVESTAV
- CONACYT
- LNS
- SEP
- UASLP
- MOS
- Ministry of Business, Innovation and Employment
- Pakistan Atomic Energy Commission
- Ministry of Science and Higher Education
- National Science Centre
- Fundatpo para a CiOncia e a Tecnologia
- JINR, Dubna
- Ministry of Education and Science of the Russian Federation
- Federal Agency of Atomic Energy of the Russian Federation
- Russian Academy of Sciences
- Russian Foundation for Basic Research
- National Research Center “Kurchatov Institute”
- Ministry of Education, Science and Technological Development of Serbia
- Secretaría de Estado de Investigación, Desarrollo e Innovación
- Programa Consolider-Ingenio 2010
- Plan de Ciencia, Tecnología e Innovación 2013–2017 del Principado de Asturias
- Fondo Europeo de Desarrollo Regional, Spain
- MOSTR
- ETH Board
- ETH Zurich
- PSI
- SNF
- UniZH
- Canton Zurich
- SER
- Ministry of Science and Technology
- Thailand Center of Excellence in Physics
- Institute for the Promotion of Teaching Science and Technology of Thailand
- Special Task Force for Activating Research
- National Science and Technology Development Agency of Thailand
- Scientific and Technical Research Council of Turkey
- Turkish Atomic Energy Authority
- National Academy of Sciences of Ukraine
- State Fund for Fundamental Researches
- Science and Technology Facilities Council
- US Department of Energy
- US National Science Foundation
- Marie-Curie programme
- European Research Council and EPLANET (European Union)
- Horizon 2020 Grant, contract no. 675440 (European Union)
- Leventis Foundation
- Alfred P. Sloan Foundation
- Alexander von Humboldt Foundation
- Belgian Federal Science Policy Office
- Fonds pour la Formation a la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium)
- Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium)
- Belgian Fonds de la Recherche Scientifique, “Excellence of Science - EOS” - be.h project n. 30820817
- Belgian Fonds voor Wetenschappelijk Onderzoek, “Excellence of Science - EOS” - be.h project n. 30820817
- Ministry of Education, Youth and Sports (MEYS) of the Czech Republic
- Lendúlet (“Momentum”) Programme and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences
- New National Excellence Program ÚNKP, the NKFIA research grants 123842, 123959, 124845, 124850 and 125105
- Council of Science and Industrial Research, India
- HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund
- National Science Center, contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406
- National Priorities Research Program by Qatar National Research Fund
- Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509
- Programa Severo Ochoa del Principado de Asturias
- Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF
- Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand)
- CUAASC
- Welch Foundation, contract C-1845
- Weston Havens Foundation
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7
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Search for third-generation scalar leptoquarks decaying to a top quark and a τ lepton at s = 13 Te . THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2018; 78:707. [PMID: 30839784 PMCID: PMC6191165 DOI: 10.1140/epjc/s10052-018-6143-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 08/08/2018] [Indexed: 06/09/2023]
Abstract
A search for pair production of heavy scalar leptoquarks (LQs), each decaying into a top quark and a τ lepton, is presented. The search considers final states with an electron or a muon, one or two τ leptons that decayed to hadrons, and additional jets. The data were collected in 2016 in proton-proton collisions ats = 13 Te with the CMS detector at the LHC, and correspond to an integrated luminosity of 35.9fb - 1 . No evidence for pair production of LQs is found. Assuming a branching fraction of unity for the decay LQ → t τ , upper limits on the production cross section are set as a function of LQ mass, excluding masses below 900Ge at 95% confidence level. These results provide the most stringent limits to date on the production of scalar LQs that decay to a top quark and a τ lepton.
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Grants
- Austrian Federal Ministry of Science, Research and Economy
- Austrian Science Fund
- Belgian Fonds de la Recherche Scientifique
- Belgian Fonds voor Wetenschappelijk Onderzoek
- CNPq
- CAPES
- FAPERJ
- FAPESP
- Bulgarian Ministry of Education and Science
- CERN
- Chinese Academy of Sciences
- Ministry of Science and Technology
- Chinese National Natural Science Foundation of China
- Colombian Funding Agency (COLCIENCIAS)
- Croatian Ministry of Science, Education and Sport
- Croatian Science Foundation
- Research Promotion Foundation
- SENESCYT
- Ministry of Education and Research
- Estonian Research Council via IUT23-4 and IUT23-6
- European Regional Development Fund
- Academy of Finland
- Finnish Ministry of Education and Culture
- Helsinki Institute of Physics
- Institut National de Physique NuclTaire et de Physique des Particules
- Centre National de la Recherche Scientifique
- Commissariat a l’+nergie Atomique et aux +nergies Alternatives
- Bundesministerium fnr Bildung und Forschung
- Deutsche Forschungsgemeinschaft
- Helmholtz-Gemeinschaft Deutscher Forschungszentren
- General Secretariat for Research and Technology
- National Scientific Research Foundation
- National Innovation Office
- Department of Atomic Energy
- Department of Science and Technology
- Institute for Research in Fundamental Studies
- Science Foundation
- Istituto Nazionale di Fisica Nucleare
- Korean Ministry of Education, Science and Technology
- National Research Foundation of Korea (NRF)
- Lithuanian Academy of Sciences
- Ministry of Education
- University of Malaya
- BUAP
- CINVESTAV
- CONACYT
- LNS
- SEP
- UASLP
- Ministry of Business, Innovation and Employment
- Pakistan Atomic Energy Commission
- Ministry of Science and Higher Education
- National Science Centre
- Fundatpo para a CiOncia e a Tecnologia
- JINR, Dubna
- Ministry of Education and Science of the Russian Federation
- Federal Agency of Atomic Energy of the Russian Federation
- Russian Academy of Sciences
- Russian Foundation for Basic Research
- Russian Competitiveness Program of National Research Nuclear University/ Moscow Engineering Physics Institute
- Ministry of Education, Science and Technological Development of Serbia
- Secretaría de Estado de Investigación, Desarrollo e Innovación
- Programa Consolider-Ingenio 2010
- Plan de Ciencia, Tecnología e Innovación 2013-2017 del Principado de Asturias
- Fondo Europeo de Desarrollo Regional, Spain
- ETH Board
- ETH Zurich
- PSI
- SNF
- UniZH
- Canton Zurich
- SER
- Ministry of Science and Technology
- Thailand Center of Excellence in Physics
- Institute for the Promotion of Teaching Science and Technology of Thailand
- Special Task Force for Activating Research
- National Science and Technology Development Agency of Thailand
- Scientific and Technical Research Council of Turkey
- Turkish Atomic Energy Authority
- National Academy of Sciences of Ukraine
- State Fund for Fundamental Researches
- Science and Technology Facilities Council
- US Department of Energy
- US National Science Foundation
- Marie-Curie programme
- European Research Council and EPLANET (European Union)
- Horizon 2020 Grant, contract No. 675440 (European Union)
- Leventis Foundation
- Alfred P. Sloan Foundation
- Alexander von Humboldt Foundation
- Belgian Federal Science Policy Office
- Fonds pour la Formation a la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium)
- Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium)
- Belgian Fonds de la Recherche Scientifique, “Excellence of Science - EOS” - be.h project n. 30820817
- Belgian Fonds voor Wetenschappelijk Onderzoek, “Excellence of Science - EOS” - be.h project n. 30820817
- Ministry of Education, Youth and Sports (MEYS) of the Czech Republic
- Lendúlet (“Momentum”) Programme and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences
- New National Excellence Program ÚNKP, the NKFIA research grants 123842, 123959, 124845, 124850 and 125105
- Council of Science and Industrial Research, India
- HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund
- National Science Center, contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406
- National Priorities Research Program by Qatar National Research Fund
- Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509
- Programa Severo Ochoa del Principado de Asturias
- Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF
- Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand)
- CUAASC
- Welch Foundation, contract C-1845
- Weston Havens Foundation
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8
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Search for Physics Beyond the Standard Model in Events with High-Momentum Higgs Bosons and Missing Transverse Momentum in Proton-Proton Collisions at 13 TeV. PHYSICAL REVIEW LETTERS 2018; 120:241801. [PMID: 29956995 DOI: 10.1103/physrevlett.120.241801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Indexed: 06/08/2023]
Abstract
A search for physics beyond the standard model in events with one or more high-momentum Higgs bosons, H, decaying to pairs of b quarks in association with missing transverse momentum is presented. The data, corresponding to an integrated luminosity of 35.9 fb^{-1}, were collected with the CMS detector at the LHC in proton-proton collisions at the center-of-mass energy sqrt[s]=13 TeV. The analysis utilizes a new b quark tagging technique based on jet substructure to identify jets from H→bb[over ¯]. Events are categorized by the multiplicity of H-tagged jets, jet mass, and the missing transverse momentum. No significant deviation from standard model expectations is observed. In the context of supersymmetry (SUSY), limits on the cross sections of pair-produced gluinos are set, assuming that gluinos decay to quark pairs, H (or Z), and the lightest SUSY particle, LSP, through an intermediate next-to-lightest SUSY particle, NLSP. With large mass splitting between the NLSP and LSP, and 100% NLSP branching fraction to H, the lower limit on the gluino mass is found to be 2010 GeV.
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9
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Search for Heavy Neutral Leptons in Events with Three Charged Leptons in Proton-Proton Collisions at sqrt[s]=13 TeV. PHYSICAL REVIEW LETTERS 2018; 120:221801. [PMID: 29906166 DOI: 10.1103/physrevlett.120.221801] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Indexed: 06/08/2023]
Abstract
A search for a heavy neutral lepton N of Majorana nature decaying into a W boson and a charged lepton is performed using the CMS detector at the LHC. The targeted signature consists of three prompt charged leptons in any flavor combination of electrons and muons. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV, with an integrated luminosity of 35.9 fb^{-1}. The search is performed in the N mass range between 1 GeV and 1.2 TeV. The data are found to be consistent with the expected standard model background. Upper limits are set on the values of |V_{eN}|^{2} and |V_{μN}|^{2}, where V_{ℓN} is the matrix element describing the mixing of N with the standard model neutrino of flavor ℓ. These are the first direct limits for N masses above 500 GeV and the first limits obtained at a hadron collider for N masses below 40 GeV.
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10
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Search for Narrow Resonances in the b-Tagged Dijet Mass Spectrum in Proton-Proton Collisions at sqrt[s]=8 TeV. PHYSICAL REVIEW LETTERS 2018; 120:201801. [PMID: 29864370 DOI: 10.1103/physrevlett.120.201801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Indexed: 06/08/2023]
Abstract
A search for narrow resonances decaying to bottom quark-antiquark pairs is presented, using a data sample of proton-proton collisions at sqrt[s]=8 TeV corresponding to an integrated luminosity of 19.7 fb^{-1}. The search is extended to masses lower than those reached in typical searches for resonances decaying into jet pairs at the LHC, by taking advantage of triggers that identify jets originating from bottom quarks. No significant excess of events is observed above the background predictions. Limits are set on the product of cross section and branching fraction to bottom quarks for spin 0, 1, and 2 resonances in the mass range of 325-1200 GeV. These results improve on the limits for resonances decaying into jet pairs in the 325-500 GeV mass range.
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11
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Search for standard model production of four top quarks with same-sign and multilepton final states in proton-proton collisions at s = 13 TeV. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2018; 78:140. [PMID: 31265001 PMCID: PMC6560706 DOI: 10.1140/epjc/s10052-018-5607-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 01/31/2018] [Indexed: 06/09/2023]
Abstract
A search for standard model production of four top quarks ( t t ¯ t t ¯ ) is reported using events containing at least three leptons ( e , μ ) or a same-sign lepton pair. The events are produced in proton-proton collisions at a center-of-mass energy of 13TeV at the LHC, and the data sample, recorded in 2016, corresponds to an integrated luminosity of 35.9fb - 1 . Jet multiplicity and flavor are used to enhance signal sensitivity, and dedicated control regions are used to constrain the dominant backgrounds. The observed and expected signal significances are, respectively, 1.6 and 1.0 standard deviations, and the t t ¯ t t ¯ cross section is measured to be 16 . 9 - 11.4 + 13.8 fb , in agreement with next-to-leading-order standard model predictions. These results are also used to constrain the Yukawa coupling between the top quark and the Higgs boson to be less than 2.1 times its expected standard model value at 95% confidence level.
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Grants
- Austrian Federal Ministry of Science, Research and Economy
- Austrian Science Fund
- Belgian Fonds de la Recherche Scientifique
- Belgian Fonds voor Wetenschappelijk Onderzoek
- CNPq
- CAPES
- FAPERJ
- FAPESP
- Bulgarian Ministry of Education and Science
- CERN
- Chinese Academy of Sciences
- Ministry of Science and Technology
- Chinese National Natural Science Foundation of China
- Colombian Funding Agency (COLCIENCIAS)
- Croatian Ministry of Science, Education and Sport
- Croatian Science Foundation
- Research Promotion Foundation
- SENESCYT
- Ministry of Education and Research
- Estonian Research Council via IUT23-4 and IUT23-6
- European Regional Development Fund
- Academy of Finland
- Finnish Ministry of Education and Culture
- Helsinki Institute of Physics
- Institut National de Physique Nucléaire et de Physique des Particules
- Centre National de la Recherche Scientifique
- Commissariat à l’Énergie Atomique et aux Énergies Alternatives
- Bundesministerium für Bildung und Forschung
- Deutsche Forschungsgemeinschaft
- Helmholtz-Gemeinschaft Deutscher Forschungszentren
- General Secretariat for Research and Technology
- National Scientific Research Foundation
- National Innovation Office
- Department of Atomic Energy
- Department of Science and Technology
- Institute for Research in Fundamental Studies
- Science Foundation
- Istituto Nazionale di Fisica Nucleare
- Korean Ministry of Education, Science and Technology
- National Research Foundation of Korea (NRF)
- Lithuanian Academy of Sciences
- Ministry of Education
- University of Malaya
- BUAP
- CINVESTAV
- CONACYT
- LNS
- SEP
- UASLP
- Ministry of Business, Innovation and Employment
- Pakistan Atomic Energy Commission
- Ministry of Science and Higher Education
- National Science Centre
- Fundaçãpo para a Ciência e a Tecnologia
- JINR, Dubna
- Ministry of Education and Science of the Russian Federation
- Federal Agency of Atomic Energy of the Russian Federation
- Russian Academy of Sciences
- Russian Foundation for Basic Research
- Russian Competitiveness Program of National Research Nuclear University/ Moscow Engineering Physics Institute
- Ministry of Education, Science and Technological Development of Serbia
- Secretaría de Estado de Investigación, Desarrollo e Innovación
- Programa Consolider-Ingenio 2010
- Plan de Ciencia, Tecnología e Innovación 2013-2017 del Principado de Asturias
- Fondo Europeo de Desarrollo Regional, Spain
- ETH Board
- ETH Zurich
- PSI
- SNF
- UniZH
- Canton Zurich
- SER
- Thailand Center of Excellence in Physics
- Institute for the Promotion of Teaching Science and Technology of Thailand
- Special Task Force for Activating Research
- National Science and Technology Development Agency of Thailand
- Scientific and Technical Research Council of Turkey
- Turkish Atomic Energy Authority
- National Academy of Sciences of Ukraine
- State Fund for Fundamental Researches
- Science and Technology Facilities Council
- US Department of Energy
- US National Science Foundation
- Marie-Curie programme
- European Research Council and EPLANET (European Union)
- Horizon 2020 Grant, contract No. 675440 (European Union)
- Leventis Foundation
- Alfred P. Sloan Foundation
- Alexander von Humboldt Foundation
- Belgian Federal Science Policy Office
- Fonds pour la Formation á la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium)
- Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium)
- Ministry of Education, Youth and Sports (MEYS) of the Czech Republic
- Council of Scientific and Industrial Research, India
- HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund
- National Science Center, contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406
- Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF
- National Priorities Research Program by Qatar National Research Fund
- Programa Severo Ochoa del Principado de Asturias
- Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand)
- CUAASC
- Welch Foundation, contract C-1845
- Weston Havens Foundation
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12
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13
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Measurement of differential cross sections for the production of a pair of isolated photons in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2014; 74:3129. [PMID: 25814874 PMCID: PMC4371070 DOI: 10.1140/epjc/s10052-014-3129-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 10/14/2014] [Indexed: 06/04/2023]
Abstract
A measurement of differential cross sections for the production of a pair of isolated photons in proton-proton collisions at [Formula: see text] is presented. The data sample corresponds to an integrated luminosity of 5.0[Formula: see text] collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25[Formula: see text] respectively, in the pseudorapidity range [Formula: see text], [Formula: see text] and with an angular separation [Formula: see text], is [Formula: see text][Formula: see text]. Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthal angle difference between the two photons, and the cosine of the polar angle in the Collins-Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics.
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14
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Evidence of b-jet quenching in PbPb collisions at √(s(NN))=2.76 TeV. PHYSICAL REVIEW LETTERS 2014; 113:132301. [PMID: 25302881 DOI: 10.1103/physrevlett.113.132301] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Indexed: 06/04/2023]
Abstract
The production of jets associated to bottom quarks is measured for the first time in PbPb collisions at a center-of-mass energy of 2.76 TeV per nucleon pair. Jet spectra are reported in the transverse momentum (p(T)) range of 80-250 GeV/c, and within pseudorapidity |η|<2. The nuclear modification factor (R(AA)) calculated from these spectra shows a strong suppression in the b-jet yield in PbPb collisions relative to the yield observed in pp collisions at the same energy. The suppression persists to the largest values of p(T) studied, and is centrality dependent. The R(AA) is about 0.4 in the most central events, similar to previous observations for inclusive jets. This implies that jet quenching does not have a strong dependence on parton mass and flavor in the jet p(T) range studied.
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15
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Measurement of jet multiplicity distributions in [Formula: see text] production in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2014; 74:3014. [PMID: 25814909 PMCID: PMC4371091 DOI: 10.1140/epjc/s10052-014-3014-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 07/30/2014] [Indexed: 06/02/2023]
Abstract
The normalised differential top quark-antiquark production cross section is measured as a function of the jet multiplicity in proton-proton collisions at a centre-of-mass energy of 7[Formula: see text] at the LHC with the CMS detector. The measurement is performed in both the dilepton and lepton+jets decay channels using data corresponding to an integrated luminosity of 5.0[Formula: see text]. Using a procedure to associate jets to decay products of the top quarks, the differential cross section of the [Formula: see text] production is determined as a function of the additional jet multiplicity in the lepton+jets channel. Furthermore, the fraction of events with no additional jets is measured in the dilepton channel, as a function of the threshold on the jet transverse momentum. The measurements are compared with predictions from perturbative quantum chromodynamics and no significant deviations are observed.
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16
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Search for invisible decays of Higgs bosons in the vector boson fusion and associated ZH production modes. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2014; 74:2980. [PMID: 25814906 PMCID: PMC4370888 DOI: 10.1140/epjc/s10052-014-2980-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 07/13/2014] [Indexed: 06/01/2023]
Abstract
A search for invisible decays of Higgs bosons is performed using the vector boson fusion and associated ZH production modes. In the ZH mode, the Z boson is required to decay to a pair of charged leptons or a [Formula: see text] quark pair. The searches use the 8 [Formula: see text] pp collision dataset collected by the CMS detector at the LHC, corresponding to an integrated luminosity of up to 19.7 [Formula: see text]. Certain channels include data from 7 [Formula: see text] collisions corresponding to an integrated luminosity of 4.9 [Formula: see text]. The searches are sensitive to non-standard-model invisible decays of the recently observed Higgs boson, as well as additional Higgs bosons with similar production modes and large invisible branching fractions. In all channels, the observed data are consistent with the expected standard model backgrounds. Limits are set on the production cross section times invisible branching fraction, as a function of the Higgs boson mass, for the vector boson fusion and ZH production modes. By combining all channels, and assuming standard model Higgs boson cross sections and acceptances, the observed (expected) upper limit on the invisible branching fraction at [Formula: see text] [Formula: see text] is found to be 0.58 (0.44) at 95 % confidence level. We interpret this limit in terms of a Higgs-portal model of dark matter interactions.
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17
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Measurement of WZ and ZZ production in pp collisions at [Formula: see text] in final states with b-tagged jets. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2014; 74:2973. [PMID: 25814904 PMCID: PMC4370898 DOI: 10.1140/epjc/s10052-014-2973-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 07/09/2014] [Indexed: 06/04/2023]
Abstract
Measurements are reported of the WZ and ZZ production cross sections in proton-proton collisions at [Formula: see text][Formula: see text] in final states where one Z boson decays to b-tagged jets. The other gauge boson, either W or Z, is detected through its leptonic decay (either [Formula: see text], [Formula: see text] or [Formula: see text], [Formula: see text], or [Formula: see text]). The results are based on data corresponding to an integrated luminosity of 18.9 fb[Formula: see text] collected with the CMS detector at the Large Hadron Collider. The measured cross sections, [Formula: see text] and [Formula: see text], are consistent with next-to-leading order quantum chromodynamics calculations.
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18
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Observation of the associated production of a single top quark and a W boson in pp collisions at sqrt[s] = 8 TeV. PHYSICAL REVIEW LETTERS 2014; 112:231802. [PMID: 24972196 DOI: 10.1103/physrevlett.112.231802] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Indexed: 06/03/2023]
Abstract
The first observation of the associated production of a single top quark and a W boson is presented. The analysis is based on a data set corresponding to an integrated luminosity of 12.2 fb(-1) of proton-proton collisions at sqrt[s] = 8 TeV recorded by the CMS experiment at the LHC. Events with two leptons and a jet originating from a b quark are selected. A multivariate analysis based on kinematic and topological properties is used to separate the signal from the dominant tt background. An excess consistent with the signal hypothesis is observed, with a significance which corresponds to 6.1 standard deviations above a background-only hypothesis. The measured production cross section is 23.4 ± 5.4 pb, in agreement with the standard model prediction.
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19
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Probing color coherence effects in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2014; 74:2901. [PMID: 25814895 PMCID: PMC4370765 DOI: 10.1140/epjc/s10052-014-2901-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 05/14/2014] [Indexed: 05/31/2023]
Abstract
A study of color coherence effects in pp collisions at a center-of-mass energy of 7[Formula: see text] is presented. The data used in the analysis were collected in 2010 with the CMS detector at the LHC and correspond to an integrated luminosity of 36 pb[Formula: see text]. Events are selected that contain at least three jets and where the two jets with the largest transverse momentum exhibit a back-to-back topology. The measured angular correlation between the second- and third-leading jet is shown to be sensitive to color coherence effects, and is compared to the predictions of Monte Carlo models with various implementations of color coherence. None of the models describe the data satisfactorily.
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20
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Study of the production of charged pions, kaons, and protons in pPb collisions at [Formula: see text]5.02[Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2014; 74:2847. [PMID: 25814892 PMCID: PMC4370925 DOI: 10.1140/epjc/s10052-014-2847-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 04/04/2014] [Indexed: 05/28/2023]
Abstract
Spectra of identified charged hadrons are measured in pPb collisions with the CMS detector at the LHC at [Formula: see text]. Charged pions, kaons, and protons in the transverse-momentum range [Formula: see text]-1.7[Formula: see text] and laboratory rapidity [Formula: see text] are identified via their energy loss in the silicon tracker. The average [Formula: see text] increases with particle mass and the charged multiplicity of the event. The increase of the average [Formula: see text] with charged multiplicity is greater for heavier hadrons. Comparisons to Monte Carlo event generators reveal that Epos Lhc, which incorporates additional hydrodynamic evolution of the created system, is able to reproduce most of the data features, unlike Hijing and Ampt. The [Formula: see text] spectra and integrated yields are also compared to those measured in pp and PbPb collisions at various energies. The average transverse momentum and particle ratio measurements indicate that particle production at LHC energies is strongly correlated with event particle multiplicity.
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22
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Measurement of inclusive W and Z boson production cross sections in pp collisions at sqrt[s] = 8 TeV. PHYSICAL REVIEW LETTERS 2014; 112:191802. [PMID: 24877930 DOI: 10.1103/physrevlett.112.191802] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Indexed: 06/03/2023]
Abstract
A measurement of total and fiducial inclusive W and Z boson production cross sections in pp collisions at sqrt[s] = 8 TeV is presented. Electron and muon final states are analyzed in a data sample collected with the CMS detector corresponding to an integrated luminosity of 18.2 ± 0.5 pb(-1). The measured total inclusive cross sections times branching fractions are σ(pp → WX)×B(W → ℓν) = 12.21 ± 0.03(stat) ± 0.24(syst) ± 0.32(lum) nb and σ(pp → ZX) × B(Z → ℓ+ℓ-) = 1.15 ± 0.01(stat) ± 0.02(syst) ± 0.03(lum) nb for the dilepton mass in the range of 60-120 GeV. The measured values agree with next-to-next-to-leading-order QCD cross section calculations. Ratios of cross sections are reported with a precision of 2%. This is the first measurement of inclusive W and Z boson production in proton-proton collisions at sqrt[s] = 8 TeV.
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23
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Measurement of theWγandZγinclusive cross sections inppcollisions ats=7 TeVand limits on anomalous triple gauge boson couplings. Int J Clin Exp Med 2014. [DOI: 10.1103/physrevd.89.092005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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24
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Measurements of tt spin correlations and top-quark polarization using dilepton final states in pp collisions at sqrt[s]=7 TeV. PHYSICAL REVIEW LETTERS 2014; 112:182001. [PMID: 24856688 DOI: 10.1103/physrevlett.112.182001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Indexed: 06/03/2023]
Abstract
Spin correlations and polarization in the top quark-antiquark system are measured using dilepton final states produced in pp collisions at the LHC at sqrt[s]=7 TeV. The data correspond to an integrated luminosity of 5.0 fb(-1) collected with the CMS detector. The measurements are performed using events with two oppositely charged leptons (electrons or muons), a significant imbalance in transverse momentum, and two or more jets, where at least one of the jets is identified as originating from a b quark. The spin correlations and polarization are measured through asymmetries in angular distributions of the two selected leptons, unfolded to the parton level. All measurements are found to be in agreement with predictions of the standard model.
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25
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Search for top-quark partners with charge 5/3 in the same-sign dilepton final state. PHYSICAL REVIEW LETTERS 2014; 112:171801. [PMID: 24836237 DOI: 10.1103/physrevlett.112.171801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Indexed: 06/03/2023]
Abstract
A search for the production of heavy partners of the top quark with charge 5/3 is performed in events with a pair of same-sign leptons. The data sample corresponds to an integrated luminosity of 19.5 fb(-1) and was collected at sqrt[s] = 8 TeV by the CMS experiment. No significant excess is observed in the data above the expected background, and the existence of top-quark partners with masses below 800 GeV is excluded at a 95% confidence level, assuming they decay exclusively to tW. This is the first limit on these particles from the LHC, and it is significantly more restrictive than previous limits.
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26
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Search for flavor-changing neutral currents in top-quark decays t → Zq in pp collisions at sqrt[s] = 8 TeV. PHYSICAL REVIEW LETTERS 2014; 112:171802. [PMID: 24836238 DOI: 10.1103/physrevlett.112.171802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Indexed: 06/03/2023]
Abstract
A search for flavor-changing neutral currents in top-quark decays t → Zq is performed in events produced from the decay chain tt → Zq+Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A data set collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7 fb(-1) of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus, no evidence for flavor-changing neutral currents in top-quark decays is found. A combination with a previous search at 7 TeV excludes a t → Zq branching fraction greater than 0.05% at the 95% confidence level.
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27
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Search for top squark and Higgsino production using diphoton Higgs boson decays. PHYSICAL REVIEW LETTERS 2014; 112:161802. [PMID: 24815637 DOI: 10.1103/physrevlett.112.161802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Indexed: 06/03/2023]
Abstract
Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top quark (the top squark) and the Higgs boson (Higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 fb-1 of proton-proton collision data at s=8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the top squark mass below 360 to 410 GeV, depending on the Higgsino mass.
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28
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Measurement of the top-quark mass in all-jets [Formula: see text] events in pp collisions at [Formula: see text] TeV. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2014; 74:2758. [PMID: 25814885 PMCID: PMC4370827 DOI: 10.1140/epjc/s10052-014-2758-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 12/31/2013] [Indexed: 06/04/2023]
Abstract
The mass of the top quark is measured using a sample of [Formula: see text] candidate events with at least six jets in the final state. The sample is selected from data collected with the CMS detector in pp collisions at [Formula: see text] TeV in 2011 and corresponds to an integrated luminosity of 3.54 [Formula: see text]. The mass is reconstructed for each event employing a kinematic fit of the jets to a [Formula: see text] hypothesis. The top-quark mass is measured to be [Formula: see text] GeV. A combination with previously published measurements in other decay modes by CMS yields a mass of [Formula: see text] GeV.
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30
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Jet and underlying event properties as a function of charged-particle multiplicity in proton-proton collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2013; 73:2674. [PMID: 25814851 PMCID: PMC4371079 DOI: 10.1140/epjc/s10052-013-2674-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 11/18/2013] [Indexed: 06/04/2023]
Abstract
Characteristics of multi-particle production in proton-proton collisions at [Formula: see text] are studied as a function of the charged-particle multiplicity, Nch. The produced particles are separated into two classes: those belonging to jets and those belonging to the underlying event. Charged particles are measured with pseudorapidity |η|<2.4 and transverse momentum pT>0.25 GeV/c. Jets are reconstructed from charged-particles only and required to have pT>5 GeV/c. The distributions of jet pT, average pT of charged particles belonging to the underlying event or to jets, jet rates, and jet shapes are presented as functions of Nch and compared to the predictions of the pythia and herwig event generators. Predictions without multi-parton interactions fail completely to describe the Nch-dependence observed in the data. For increasing Nch, pythia systematically predicts higher jet rates and harder pT spectra than seen in the data, whereas herwig shows the opposite trends. At the highest multiplicity, the data-model agreement is worse for most observables, indicating the need for further tuning and/or new model ingredients.
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31
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Search for top squarks in R-parity-violating supersymmetry using three or more leptons and b-tagged jets. PHYSICAL REVIEW LETTERS 2013; 111:221801. [PMID: 24329437 DOI: 10.1103/physrevlett.111.221801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Indexed: 06/03/2023]
Abstract
A search for anomalous production of events with three or more isolated leptons and bottom-quark jets produced in pp collisions at √s=8 TeV is presented. The analysis is based on a data sample corresponding to an integrated luminosity of 19.5 fb(-1) collected by the CMS experiment at the LHC in 2012. No excess above the standard model expectations is observed. The results are interpreted in the context of supersymmetric models with signatures that have low missing transverse energy arising from light top-squark pair production with R-parity-violating decays of the lightest supersymmetric particle. In two models with different R-parity-violating couplings, top squarks are excluded below masses of 1020 GeV and 820 GeV when the lightest supersymmetric particle has a mass of 200 GeV.
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32
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Searches for new physics using the tt¯ invariant mass distribution in pp collisions at √s=8 TeV. PHYSICAL REVIEW LETTERS 2013; 111:211804. [PMID: 24313480 DOI: 10.1103/physrevlett.111.211804] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Indexed: 06/02/2023]
Abstract
Searches for anomalous top quark-antiquark production are presented, based on pp collisions at √s=8 TeV. The data, corresponding to an integrated luminosity of 19.7 fb(-1), were collected with the CMS detector at the LHC. The observed tt¯ invariant mass spectrum is found to be compatible with the standard model prediction. Limits on the production cross section times branching fraction probe, for the first time, a region of parameter space for certain models of new physics not yet constrained by precision measurements.
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33
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Search for supersymmetry in hadronic final states with missing transverse energy using the variables αT and b-quark multiplicity in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2013; 73:2568. [PMID: 25814868 PMCID: PMC4371056 DOI: 10.1140/epjc/s10052-013-2568-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 08/14/2013] [Indexed: 06/01/2023]
Abstract
An inclusive search for supersymmetric processes that produce final states with jets and missing transverse energy is performed in pp collisions at a centre-of-mass energy of 8 TeV. The data sample corresponds to an integrated luminosity of 11.7 fb-1 collected by the CMS experiment at the LHC. In this search, a dimensionless kinematic variable, αT, is used to discriminate between events with genuine and misreconstructed missing transverse energy. The search is based on an examination of the number of reconstructed jets per event, the scalar sum of transverse energies of these jets, and the number of these jets identified as originating from bottom quarks. No significant excess of events over the standard model expectation is found. Exclusion limits are set in the parameter space of simplified models, with a special emphasis on both compressed-spectrum scenarios and direct or gluino-induced production of third-generation squarks. For the case of gluino-mediated squark production, gluino masses up to 950-1125 GeV are excluded depending on the assumed model. For the direct pair-production of squarks, masses up to 450 GeV are excluded for a single light first- or second-generation squark, increasing to 600 GeV for bottom squarks.
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34
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Measurement of the Bs(0)→μ+ μ- branching fraction and search for B(0)→μ+ μ- with the CMS experiment. PHYSICAL REVIEW LETTERS 2013; 111:101804. [PMID: 25166654 DOI: 10.1103/physrevlett.111.101804] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Indexed: 06/03/2023]
Abstract
Results are presented from a search for the rare decays Bs(0)→μ+ μ- and B(0)→μ+ μ- in pp collisions at sqrt[s]=7 and 8 TeV, with data samples corresponding to integrated luminosities of 5 and 20 fb(-1), respectively, collected by the CMS experiment at the LHC. An unbinned maximum-likelihood fit to the dimuon invariant mass distribution gives a branching fraction B(Bs(0)→μ+ μ-)=(3.0(-0.9)(+1.0))×10(-9), where the uncertainty includes both statistical and systematic contributions. An excess of Bs(0)→μ+ μ- events with respect to background is observed with a significance of 4.3 standard deviations. For the decay B(0)→μ+ μ- an upper limit of B(B(0)→μ+ μ-)<1.1×10(-9) at the 95% confidence level is determined. Both results are in agreement with the expectations from the standard model.
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35
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Inclusive search for supersymmetry using razor variables in pp collisions at √s=7 TeV. PHYSICAL REVIEW LETTERS 2013; 111:081802. [PMID: 24010428 DOI: 10.1103/physrevlett.111.081802] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Indexed: 06/02/2023]
Abstract
An inclusive search is presented for new heavy particle pairs produced in √s=7 TeV proton-proton collisions at the LHC using 4.7±0.1 fb(-1) of integrated luminosity. The selected events are analyzed in the 2D razor space of M(R), an event-by-event indicator of the heavy particle mass scale, and R, a dimensionless variable related to the missing transverse energy. The third-generation sector is probed using the event heavy-flavor content. The search is sensitive to generic supersymmetry models with minimal assumptions about the superpartner decay chains. No excess is observed in the number of events beyond that predicted by the standard model. Exclusion limits are derived in the CMSSM framework as well as for simplified models. Within the CMSSM parameter space considered, gluino masses up to 800 GeV and squark masses up to 1.35 TeV are excluded at 95% confidence level depending on the model parameters. The direct production of pairs of top or bottom squarks is excluded for masses as high as 400 GeV.
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36
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Search for physics beyond the standard model in events with τ leptons, jets, and large transverse momentum imbalance in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2013; 73:2493. [PMID: 25814865 PMCID: PMC4370880 DOI: 10.1140/epjc/s10052-013-2493-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 06/11/2013] [Indexed: 06/04/2023]
Abstract
A search for physics beyond the standard model is performed with events having one or more hadronically decaying τ leptons, highly energetic jets, and large transverse momentum imbalance. The data sample corresponds to an integrated luminosity of 4.98 fb-1 of proton-proton collisions at [Formula: see text] collected with the CMS detector at the LHC in 2011. The number of observed events is consistent with predictions for standard model processes. Lower limits on the mass of the gluino in supersymmetric models are determined.
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37
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Measurement of masses in the [Formula: see text] system by kinematic endpoints in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2013; 73:2494. [PMID: 25814866 PMCID: PMC4371053 DOI: 10.1140/epjc/s10052-013-2494-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Revised: 06/18/2013] [Indexed: 06/04/2023]
Abstract
A simultaneous measurement of the top-quark, W-boson, and neutrino masses is reported for [Formula: see text] events selected in the dilepton final state from a data sample corresponding to an integrated luminosity of 5.0 fb-1 collected by the CMS experiment in pp collisions at [Formula: see text]. The analysis is based on endpoint determinations in kinematic distributions. When the neutrino and W-boson masses are constrained to their world-average values, a top-quark mass value of [Formula: see text] is obtained. When such constraints are not used, the three particle masses are obtained in a simultaneous fit. In this unconstrained mode the study serves as a test of mass determination methods that may be used in beyond standard model physics scenarios where several masses in a decay chain may be unknown and undetected particles lead to underconstrained kinematics.
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38
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Search for a standard-model-like Higgs boson with a mass in the range 145 to 1000 GeV at the LHC. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2013; 73:2469. [PMID: 25814864 PMCID: PMC4370850 DOI: 10.1140/epjc/s10052-013-2469-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 05/04/2013] [Indexed: 06/04/2023]
Abstract
A search for a standard-model-like Higgs boson in the H→WW and H→ZZ decay channels is reported, for Higgs boson masses in the range 145
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39
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Search for supersymmetry in pp collisions at [Formula: see text] TeV in events with a single lepton, jets, and missing transverse momentum. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2013; 73:2404. [PMID: 25814857 PMCID: PMC4370766 DOI: 10.1140/epjc/s10052-013-2404-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 03/02/2013] [Indexed: 05/30/2023]
Abstract
Results are reported from a search for new physics processes in events containing a single isolated high-transverse-momentum lepton (electron or muon), energetic jets, and large missing transverse momentum. The analysis is based on a 4.98 fb-1 sample of proton-proton collisions at a center-of-mass energy of 7 TeV, obtained with the CMS detector at the LHC. Three separate background estimation methods, each relying primarily on control samples in the data, are applied to a range of signal regions, providing complementary approaches for estimating the background yields. The observed yields are consistent with the predicted standard model backgrounds. The results are interpreted in terms of limits on the parameter space for the constrained minimal supersymmetric extension of the standard model, as well as on cross sections for simplified models, which provide a generic description of the production and decay of new particles in specific, topology based final states. ELECTRONIC SUPPLEMENTARY MATERIAL The online version of this article (doi:10.1140/epjc/s10052-013-2404-z) contains supplementary material, which is available to authorized users.
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40
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Measurement of associated production of vector bosons and top quark-antiquark pairs in pp collisions at sqrt[s]=7 TeV. PHYSICAL REVIEW LETTERS 2013; 110:172002. [PMID: 23679709 DOI: 10.1103/physrevlett.110.172002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Indexed: 06/02/2023]
Abstract
The first measurement of vector-boson production associated with a top quark-antiquark pair in proton-proton collisions at sqrt[s] = 7 TeV is presented. The results are based on a data set corresponding to an integrated luminosity of 5.0 fb(-1), recorded by the CMS detector at the LHC in 2011. The measurement is performed in two independent channels through a trilepton analysis of ttZ events and a same-sign dilepton analysis of ttV (V = W or Z) events. In the trilepton channel a direct measurement of the ttZ cross section σ(ttZ) = 0.28(-0.11)(+0.14) (stat)(-0.03)(+0.06) (syst) pb is obtained. In the dilepton channel a measurement of the ttV cross section yields σ(ttV) = 0.43(-0.15)(+0.17) (stat)(-0.07)(+0.09) (syst) pb. These measurements have a significance, respectively, of 3.3 and 3.0 standard deviations from the background hypotheses and are compatible, within uncertainties, with the corresponding next-to-leading order predictions of 0.137(-0.016)(+0.012) and 0.306(-0.053)(+0.031) pb.
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41
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Search for new physics in final states with a lepton and missing transverse energy inppcollisions at the LHC. Int J Clin Exp Med 2013. [DOI: 10.1103/physrevd.87.072005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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42
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Search for pair-produced dijet resonances in four-jet final states in pp collisions at sqrt[s] = 7 TeV. PHYSICAL REVIEW LETTERS 2013; 110:141802. [PMID: 25166980 DOI: 10.1103/physrevlett.110.141802] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Indexed: 06/03/2023]
Abstract
A search for the pair production of a heavy, narrow resonance decaying into two jets has been performed using events collected in sqrt[s] = 7 TeV pp collisions with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 5.0 fb(-1). Events are selected with at least four jets and two dijet combinations with similar dijet mass. No resonances are found in the dijet mass spectrum. The upper limit at 95% confidence level on the product of the resonance pair production cross section, the branching fractions into dijets, and the acceptance varies from 0.22 to 0.005 pb, for resonance masses between 250 and 1200 GeV. Pair-produced colorons decaying into qq are excluded for coloron masses between 250 and 740 GeV.
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43
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Search for contact interactions using the inclusive jetpTspectrum inppcollisions ats=7 TeV. Int J Clin Exp Med 2013. [DOI: 10.1103/physrevd.87.052017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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44
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Search for pair production of third-generation leptoquarks and top squarks in pp collisions at sqrt[s] = 7 TeV. PHYSICAL REVIEW LETTERS 2013; 110:081801. [PMID: 23473129 DOI: 10.1103/physrevlett.110.081801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Indexed: 06/01/2023]
Abstract
Results are presented from a search for the pair production of third-generation scalar and vector leptoquarks, as well as for top squarks in R-parity-violating supersymmetric models. In either scenario, the new, heavy particle decays into a τ lepton and a b quark. The search is based on a data sample of pp collisions at sqrt[s] = 7 TeV, which is collected by the CMS detector at the LHC and corresponds to an integrated luminosity of 4.8 fb(-1). The number of observed events is found to be in agreement with the standard model prediction, and exclusion limits on mass parameters are obtained at the 95% confidence level. Vector leptoquarks with masses below 760 GeV are excluded and, if the branching fraction of the scalar leptoquark decay to a τ lepton and a b quark is assumed to be unity, third-generation scalar leptoquarks with masses below 525 GeV are ruled out. Top squarks with masses below 453 GeV are excluded for a typical benchmark scenario, and limits on the coupling between the top squark, τ lepton, and b quark, λ(333)(') are obtained. These results are the most stringent for these scenarios to date.
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Measurement of the Υ1S, Υ2S, and Υ3S polarizations in pp collisions at sqrt[s] = 7 TeV. PHYSICAL REVIEW LETTERS 2013; 110:081802. [PMID: 23473130 DOI: 10.1103/physrevlett.110.081802] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Indexed: 06/01/2023]
Abstract
The polarizations of the Υ(1S), Υ(2S), and Υ(3S) mesons are measured in proton-proton collisions at sqrt[s] = 7 TeV, using a data sample of Υ(nS) → μ +μ- decays collected by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb(-1). The dimuon decay angular distributions are analyzed in three different polarization frames. The polarization parameters λ[symbol see text], λ(φ), and λ([symbol see text]φ), as well as the frame-invariant quantity λ, are presented as a function of the Υ(nS) transverse momentum between 10 and 50 GeV, in the rapidity ranges |y|<0.6 and 0.6<|y|<1.2. No evidence of large transverse or longitudinal polarizations is seen in the explored kinematic region.
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Study of the mass and spin-parity of the Higgs boson candidate via its decays to Z boson pairs. PHYSICAL REVIEW LETTERS 2013; 110:081803. [PMID: 23473131 DOI: 10.1103/physrevlett.110.081803] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Indexed: 06/01/2023]
Abstract
A study is presented of the mass and spin-parity of the new boson recently observed at the LHC at a mass near 125 GeV. An integrated luminosity of 17.3 fb(-1), collected by the CMS experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, is used. The measured mass in the ZZ channel, where both Z bosons decay to e or μ pairs, is 126.2 ± 0.6(stat) ± 0.2(syst) GeV. The angular distributions of the lepton pairs in this channel are sensitive to the spin-parity of the boson. Under the assumption of spin 0, the present data are consistent with the pure scalar hypothesis, while disfavoring the pure pseudoscalar hypothesis.
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Measurement of the sum of WW and WZ production with W+dijet events in pp collisions at [Formula: see text]. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS 2013; 73:2283. [PMID: 25814853 PMCID: PMC4370803 DOI: 10.1140/epjc/s10052-013-2283-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 12/20/2012] [Indexed: 06/02/2023]
Abstract
A measurement of the inclusive WW+WZ diboson production cross section in proton-proton collisions is reported, based on events containing a leptonically decaying W boson and exactly two jets. The data sample, collected at [Formula: see text] with the CMS detector at the LHC, corresponds to an integrated luminosity of 5.0 fb-1. The measured value of the sum of the inclusive WW and WZ cross sections is σ(pp→WW+WZ)=68.9±8.7 (stat.)±9.7 (syst.)±1.5 (lum.) pb, consistent with the standard model prediction of 65.6±2.2 pb. This is the first measurement of WW+WZ production in pp collisions using this signature. No evidence for anomalous triple gauge couplings is found and upper limits are set on their magnitudes.
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Measurement of the azimuthal anisotropy of neutral pions in Pb-Pb collisions at sqrt[s](NN)] = 2.76 TeV. PHYSICAL REVIEW LETTERS 2013; 110:042301. [PMID: 25166155 DOI: 10.1103/physrevlett.110.042301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Indexed: 06/03/2023]
Abstract
First measurements of the azimuthal anisotropy of neutral pions produced in Pb-Pb collisions at a center-of-mass energy of sqrt[s(NN)] = 2.76 TeV are presented. The amplitudes of the second Fourier component (v(2)) of the π(0) azimuthal distributions are extracted using an event-plane technique. The values of v(2) are studied as a function of the neutral pion transverse momentum (p(T)) for different classes of collision centrality in the kinematic range 1.6<p(T) <8.0 GeV/c, within the pseudorapidity interval |η|<0.8. The CMS measurements of v(2) (p(T)) are similar to previously reported π(0) azimuthal anisotropy results from sqrt[s(NN)] = 200 GeV Au-Au collisions at RHIC, despite a factor of ∼ 14 increase in the center-of-mass energy. In the momentum range 2.5<p(T)<5.0 GeV/c, the neutral pion anisotropies are found to be smaller than those observed by CMS for inclusive charged particles.
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Evidence for associated production of a single top quark and W boson in pp collisions at sqrt[s]=7 TeV. PHYSICAL REVIEW LETTERS 2013; 110:022003. [PMID: 23383893 DOI: 10.1103/physrevlett.110.022003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Indexed: 06/01/2023]
Abstract
Evidence is presented for the associated production of a single top quark and W boson in pp collisions at sqrt[s]=7 TeV with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 4.9 fb(-1). The measurement is performed using events with two leptons and a jet originated from a b quark. A multivariate analysis based on kinematic properties is utilized to separate the tt background from the signal. The observed signal has a significance of 4.0σ and corresponds to a cross section of 16(-4)(+5) pb, in agreement with the standard model expectation of 15.6±0.4(-1.2)(+1.0) pb.
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