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

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

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 t[¯ overt] dilepton final state with proton–proton collision data at √s=8 TeV from an integrated luminosity of 19.7 fb[superscript −1], col...

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Bibliographic Details
Main Authors: Apyan, Aram, Barbieri, Richard Alexander, Bauer, Gerry P, Busza, Wit, Cali, Ivan Amos, Di Matteo, Leonardo, Dutta, Valentina, Gomez-Ceballos, Guillelmo, Goncharov, Maxim, Gulhan, Doga Can, Klute, Markus, Lai, Yue Shi, Lee, Yen-Jie, Levin, Andrew Michael, Luckey Jr, P David, Ma, Teng, Paus, Christoph M. E., Ralph, Duncan Kelley, Roland, Christof E, Roland, Gunther M, Stephans, George S. F., Stoeckli, Fabian, Sumorok, Konstanty C, Velicanu, Dragos Alexandru, Veverka, Jan, Wyslouch, Boleslaw, Yang, Mingming, Zanetti, Marco, Wyslouch, Victoria, Chan, M.
Other Authors: Massachusetts Institute of Technology. Department of Physics
Format: Article
Published: Elsevier BV 2018
Online Access:http://hdl.handle.net/1721.1/117038
https://orcid.org/0000-0002-9418-6656
https://orcid.org/0000-0002-7945-005X
https://orcid.org/0000-0002-3831-9071
https://orcid.org/0000-0002-2822-3375
https://orcid.org/0000-0001-9236-6621
https://orcid.org/0000-0002-0869-5631
https://orcid.org/0000-0003-1486-606X
https://orcid.org/0000-0003-2593-7767
https://orcid.org/0000-0002-1136-6900
https://orcid.org/0000-0002-6047-4211
https://orcid.org/0000-0001-8983-2169
https://orcid.org/0000-0003-3106-4894
https://orcid.org/0000-0002-1260-777X
https://orcid.org/0000-0003-3681-0649
https://orcid.org/0000-0001-6332-5839
Description
Summary: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 t[¯ overt] dilepton final state with proton–proton collision data at √s=8 TeV from an integrated luminosity of 19.7 fb[superscript −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 |V[subscript 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[subscript t] =1.36±0.02(stat.) −0.11 +0.14 (syst.) GeV.

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