Measurement of the ratio B(t→Wb)/B(t→Wq) in pp collisions at s=8 TeV

CMS Collaboration

Research output: Contribution to journalArticlepeer-review

67 Citations (Scopus)

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 languageEnglish
Pages (from-to)33-57
Number of pages25
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume736
DOIs
Publication statusPublished - 7 Sept 2014
Externally publishedYes

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 .

FundersFunder number
Not addedST/H00081X/2
CPAN
MSES
MoERSF0690030s09
STAR
National Science Foundation1306040, 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 CouncilST/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 Forschung146730, 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

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