Abstract
The ratio of the top-quark branching fractions R=B(t→Wb)/B(t→Wq), where the denominator includes the sum over all down-type quarks (q=b,s,d), is measured in the tt¯ dilepton final state with proton–proton collision data at s=8 TeV from an integrated luminosity of 19.7 fb−1, collected with the CMS detector. In order to quantify the purity of the signal sample, the cross section is measured by fitting the observed jet multiplicity, thereby constraining the signal and background contributions. By counting the number of b jets per event, an unconstrained value of R=1.014±0.003(stat.)±0.032(syst.) is measured, in a good agreement with current precision measurements in electroweak and flavour sectors. A lower limit R>0.955 at the 95% confidence level is obtained after requiring R≤1, and a lower limit on the Cabibbo–Kobayashi–Maskawa matrix element |Vtb|>0.975 is set at 95% confidence level. The result is combined with a previous CMS measurement of the t-channel single-top-quark cross section to determine the top-quark total decay width, Γt=1.36±0.02(stat.)−0.11 +0.14(syst.) GeV.
Original language | English |
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Pages (from-to) | 33-57 |
Number of pages | 25 |
Journal | Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics |
Volume | 736 |
DOIs | |
Publication status | Published - 7 Sept 2014 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2014 The Authors
Funding
Individuals have received support from the Marie-Curie programme and the European Research Council and EPLANET (European Union); the Leventis Foundation; the Alfred P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); the HOMING PLUS programme of Foundation For Polish Science, cofinanced by EU, Regional Development Fund; and the Thalis and Aristeia programmes cofinanced by EU–ESF and the Greek NSRF. We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS institutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); Fonds De La Recherche Scientifique - FNRS and FWO (Belgium); CNPq , CAPES , FAPERJ , and FAPESP (Brazil); MES (Bulgaria); CERN ; CAS , MOST , and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); MoER , SF0690030s09 and ERDF (Estonia); Academy of Finland , MEC , and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF , DFG , and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV , CONACYT , SEP , and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON , RosAtom , RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter , IPST , STAR and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie programme and the European Research Council and EPLANET (European Union); the Leventis Foundation ; the Alfred P. Sloan Foundation ; the Alexander von Humboldt Foundation ; the Belgian Federal Science Policy Office ; the Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research , India; the Compagnia di San Paolo (Torino); the HOMING PLUS programme of Foundation For Polish Science , cofinanced by EU, Regional Development Fund ; and the Thalis and Aristeia programmes cofinanced by EU–ESF and the Greek NSRF .
Funders | Funder number |
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Not added | ST/H00081X/2 |
CPAN | |
MSES | |
MoER | SF0690030s09 |
STAR | |
National Science Foundation | 1306040, 1151640, 1314131, 0906479, 1306951, 1205960, 1120138 |
National Institutes of Health | |
U.S. Department of Energy | |
Alfred P. Sloan Foundation | |
Hispanics in Philanthropy | |
Human Growth Foundation | |
Alexander von Humboldt-Stiftung | |
California Department of Fish and Wildlife | |
University of Mississippi | |
Western Carolina University | |
Ministry of Science and Technology | |
Compagnia di San Paolo | |
Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS) | |
Children's Specialists Foundation | |
California Earthquake Authority | |
Direktion für Entwicklung und Zusammenarbeit | |
Center for African Studies | |
Ministry of Education | |
Secretaría de Educación Pública | |
Türkiye Atom Enerjisi Kurumu | |
Santa Fe Institute | |
Louisiana Academy of Sciences | |
Rochester Academy of Science | |
National Research Foundation | |
Missouri University of Science and Technology | |
CERN | |
Thailand Center of Excellence in Physics | |
Cosmetic Surgery Foundation | |
Institute for the Promotion of Teaching Science and Technology | |
Ministerstwo Obrony Narodowej | |
Science and Technology Facilities Council | ST/F006748/1, ST/L00609X/1, ST/I000410/1, ST/J004901/1, ST/G502347/1, ST/K003542/1, ST/K001256/1, ST/K003844/1, GRIDPP, ST/I505580/1, ST/I002200/1, ST/I505572/1, ST/I005912/1, ST/J005665/1, ST/K001604/1, ST/K001639/1, ST/L005603/1, ST/L006340/1, ST/F007094/1 |
European Commission | |
European Research Council | |
Department of Science and Technology, Ministry of Science and Technology, India | |
Council of Scientific and Industrial Research, India | |
Ministry of Education - Singapore | |
Department of Atomic Energy, Government of India | |
Science Foundation Ireland | |
Helmholtz-Gemeinschaft | |
Deutsche Forschungsgemeinschaft | |
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung | 146730, 153664 |
Fundação de Amparo à Pesquisa do Estado de São Paulo | |
National Natural Science Foundation of China | |
Research Promotion Foundation | |
Ministerstvo Školství, Mládeže a Tělovýchovy | |
National Science Council | |
Fundacja na rzecz Nauki Polskiej | |
Fundação para a Ciência e a Tecnologia | |
Russian Foundation for Basic Research | |
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |
Academy of Finland | |
Bundesministerium für Bildung und Forschung | |
Chinese Academy of Sciences | |
Austrian Science Fund | |
Fonds De La Recherche Scientifique - FNRS | |
Russian Academy of Sciences | |
Belgian Federal Science Policy Office | |
Fonds Wetenschappelijk Onderzoek | |
Agentschap voor Innovatie door Wetenschap en Technologie | |
Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture | |
Consejo Nacional de Ciencia y Tecnología | |
Ministerio de Educación, Cultura y Deporte | |
Bundesministerium für Wissenschaft, Forschung und Wirtschaft | |
General Secretariat for Research and Technology | |
Ministry of Business, Innovation and Employment | |
Hungarian Scientific Research Fund | |
Conselho Nacional de Desenvolvimento Científico e Tecnológico | |
National Research Foundation of Korea | |
Joint Institute for Nuclear Research | |
Instituto Nazionale di Fisica Nucleare | |
Medical Engineering Centre, King’s College London | |
A.G. Leventis Foundation | |
National Science and Technology Development Agency | |
Universiti Malaya | |
Türkiye Bilimsel ve Teknolojik Araştirma Kurumu | |
Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja | |
Ministerstwo Edukacji i Nauki | |
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro | |
Ministry of Science and Technology, Taiwan | |
National Academy of Sciences of Ukraine | |
Centre National de la Recherche Scientifique | |
European Social Fund | |
Universidad Autónoma de San Luis Potosí | |
Ministry of Education and Science | |
Institute for Research in Fundamental Sciences | |
Commissariat à l'Énergie Atomique et aux Énergies Alternatives | |
Bundesministerium für Bildung und Frauen | |
Secretaría de Estado de Investigación, Desarrollo e Innovación | |
European Regional Development Fund | |
State Atomic Energy Corporation ROSATOM | |
Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional | |
Pakistan Atomic Energy Commission | |
State Fund for Fundamental Research of Ukraine | |
Department of Science and Technology, Government of West Bengal | |
Fundació Catalana de Trasplantament | |
Institut National de Physique Nucléaire et de Physique des Particules |
Keywords
- CKM
- CMS
- Top
- Width