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Published September 7, 2014 | Submitted + Published
Journal Article Open

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

Abstract

The ratio of the top-quark branching fractions R=B(t→Wb)/B(t→Wq)R=B(t→Wb)/B(t→Wq), where the denominator includes the sum over all down-type quarks (q=b,s,dq=b,s,d), is measured in the tt dilepton final state with proton–proton collision data at √s=8TeV 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>0.955R>0.955 at the 95% confidence level is obtained after requiring R≤1R≤1, and a lower limit on the Cabibbo–Kobayashi–Maskawa matrix element |V_(tb)|>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, Γ_t=1.36 ±0.02 (stat.)^(+0.14)_(−0.11)(syst.)GeV.

Additional Information

© 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/). Funded by SCOAP3. Received 8 April 2014, Revised form 5 June 2014, Accepted 29 June 2014, Available online 3 July 2014. Editor:M. Doser. We congratulate our colleagues in the CERN accelerator depart-ments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS in-stitutes 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 construc-tion 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.

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Published - 1-s2.0-S037026931400481X-main.pdf

Submitted - 1404.2292v2.pdf

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Created:
August 22, 2023
Modified:
October 17, 2023