Measurement of the ratio B(t - GT Wb)/B(t - GT Wq) in pp collisions at root s=8 TeV
CMS Collaboration (ukupan broj autora: 2128)
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The ratio of the top-quark branching fractions R = B(t -- GT Wb)/B(t -- GT Wq), where the denominator includes the sum over all down-type quarks (q = b, s, d), is measured in the t (t) over bar dilepton final state with proton-proton collision data at root 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 GT 0.955 at the 95% confidence level is obtained after requiring R LT = 1, and a lower limit on the Cabibbo-Kobayashi-Maskawa matrix element |V-tb| GT 0.975 is set at 95% confidence level. The result is combined with a previous C...MS measurement of the t-channel single-top-quark cross section to determine the top-quark total decay width, Gamma(t) = 1.36 +/- 0.02 (stat.)(-0.11)(+0.14) (syst.) GeV. (C) 2014 The Authors. Published by Elsevier B.V.
Кључне речи:CMS / Top / CKM / Width
Извор:Physics Letters B, 2014, 736, 33-57
- BMWFW (Austria), FWF (Austria), Fonds De La Recherche Scientifique - FNRS and FWO (Belgium), CNPq (Brazil), CAPES (Brazil), FAPERJ (Brazil), FAPESP (Brazil), MES (Bulgaria), CERN (China), CAS (China), MOST (China), NSFC (China), COLCIENCIAS (Colombia), MSES (Croatia), CSF (Croatia), RPF (Cyprus), MoER (Estonia) [SF0690030s09], ERDF (Estonia), Academy of Finland, MEC (Finland), HIP (Finland), CEA (France), CNRS/IN2P3 (France), BMBF, Germany, DFG (Germany), HGF (Germany), GSRT (Greece), OTKA (Hungary), NIH (Hungary), DAE (India), DST (India), IPM (Iran), SFI (Ireland), INFN (Italy), NRF (Republic of Korea), WCU (Republic of Korea), LAS (Lithuania), MOE (Malaysia), UM (Malaysia), CINVESTAV (Mexico), CONACYT (Mexico), SEP (Mexico), UASLP- FAI (Mexico), MBIE (New Zealand), PAEC (Pakistan), MSHE (Poland), NSC (Poland), FCT (Portugal), JINR (Dubna), MON (Russia), RosAtom (Russia), RAS (Russia), RFBR (Russia), MESTD (Serbia), SEIDI (Spain), CPAN (Spain), Swiss Funding Agencies (Switzerland), MST (Taipei), ThEPCenter (Thailand), IPST (Thailand), STAR (Thailand), NSTDA (Thailand), TUBITAK (Turkey), TAEK (Turkey), NASU (Ukraine), SFFR (Ukraine), STFC (United Kingdom), DOE (USA), NSF (USA), Marie-Curie programme, European Research Council, EPLANET (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 lIndustrie et dans lAgriculture (FRIA-Belgium), Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium), Ministry of Education, Youth and Sports (MEYS) of Czech Republic, Council of Science and Industrial Research, India, Compagnia di San Paolo (Torino), HOMING PLUS programme of Foundation For Polish Science - EU, Regional Development Fund, Thalis and Aristeia programmes - EU-ESF, Greek NSRF