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Measurement of CKM matrix elements in single top quark $t$-channel production in proton-proton collisions at $\sqrt{s} = $ 13 TeV

The CMS collaboration
Phys.Lett.B 808 (2020) 135609, 2020.

Abstract (data abstract)
The first direct, model-independent measurement is presented of the modulus of the Cabibbo--Kobayashi--Maskawa (CKM) matrix elements $|V_{tb}|$, $|V_{td}|$, and $|V_{ts}|$, in final states enriched in single top quark $t$-channel events. The analysis uses proton-proton collision data from the LHC, collected during 2016 by the CMS experiment, at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $35.9 fb^{-1}$. Processes directly sensitive to these matrix elements are considered at both the production and decay vertices of the top quark. In the standard model hypothesis of CKM unitarity, a lower limit of $|V_{tb}| > 0.970$ is measured at the $95\%$ confidence level. Several theories beyond the standard model are considered, and by releasing all constraints among the involved parameters, the values $|V_{tb}| = 0.988 \pm 0.024 $, and $|V_{td}|^2 +|V_{ts}|^2 = 0.06 \pm 0.06$, where the uncertainties include both statistical and systematic components, are measured.

  • Figure 2a

    Data from Figure 2 (upper left), located on page 8.

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    The $m_{W}^{T}$ distribution from data (points) and simulation (shaded histograms) in the 2j1t (left) and 3j1t (right) categories for the...

  • Figure 2b

    Data from Figure 2 (upper right), located on page 8.

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    The $m_{W}^{T}$ distribution from data (points) and simulation (shaded histograms) in the 2j1t (left) and 3j1t (right) categories for the...

  • Figure 2c

    Data from Figure 2 (lower left), located on page 8.

    10.17182/hepdata.95117.v1/t3

    The $m_{W}^{T}$ distribution from data (points) and simulation (shaded histograms) in the 2j1t (left) and 3j1t (right) categories for the...

  • Figure 2d

    Data from Figure 2 (lower right), located on page 8.

    10.17182/hepdata.95117.v1/t4

    The $m_{W}^{T}$ distribution from data (points) and simulation (shaded histograms) in the 2j1t (left) and 3j1t (right) categories for the...

  • Figure 3a

    Data from Figure 3 (upper left), located on page 10.

    10.17182/hepdata.95117.v1/t5

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 2j1t category: the $|\eta|$...

  • Figure 3b

    Data from Figure 3 (upper right), located on page 10.

    10.17182/hepdata.95117.v1/t6

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 2j1t category: the $|\eta|$...

  • Figure 3c

    Data from Figure 3 (lower left), located on page 10.

    10.17182/hepdata.95117.v1/t7

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 2j1t category: the $|\eta|$...

  • Figure 3d

    Data from Figure 3 (lower right), located on page 10.

    10.17182/hepdata.95117.v1/t8

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 2j1t category: the $|\eta|$...

  • Figure 4a

    Data from Figure 4 (upper left), located on page 11.

    10.17182/hepdata.95117.v1/t9

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 3j1t category: the $p_{T}^{miss}$...

  • Figure 4b

    Data from Figure 4 (upper right), located on page 11.

    10.17182/hepdata.95117.v1/t10

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 3j1t category: the $p_{T}^{miss}$...

  • Figure 4c

    Data from Figure 4 (lower left), located on page 11.

    10.17182/hepdata.95117.v1/t11

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 3j1t category: the $p_{T}^{miss}$...

  • Figure 4d

    Data from Figure 4 (lower right), located on page 11.

    10.17182/hepdata.95117.v1/t12

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 3j1t category: the $p_{T}^{miss}$...

  • Figure 5a

    Data from Figure 5 (upper left), located on page 12.

    10.17182/hepdata.95117.v1/t13

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 3j2t category: the $|\eta|$...

  • Figure 5b

    Data from Figure 5 (upper right), located on page 12.

    10.17182/hepdata.95117.v1/t14

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 3j2t category: the $|\eta|$...

  • Figure 5c

    Data from Figure 5 (lower left), located on page 12.

    10.17182/hepdata.95117.v1/t15

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 3j2t category: the $|\eta|$...

  • Figure 5d

    Data from Figure 5 (lower right), located on page 12.

    10.17182/hepdata.95117.v1/t16

    Distributions of the two most discriminating variables from data (points) and simulation (shaded histograms) in the 3j2t category: the $|\eta|$...

  • Figure 6a

    Data from Figure 6 (upper left), located on page 15.

    10.17182/hepdata.95117.v1/t17

    Distribution of the multivariate discriminators, comparing data to simulation normalised after the fit procedure, for the muon channel on the...

  • Figure 6b

    Data from Figure 6 (upper right), located on page 15.

    10.17182/hepdata.95117.v1/t18

    Distribution of the multivariate discriminators, comparing data to simulation normalised after the fit procedure, for the muon channel on the...

  • Figure 6c

    Data from Figure 6 (middle left), located on page 15.

    10.17182/hepdata.95117.v1/t19

    Distribution of the multivariate discriminators, comparing data to simulation normalised after the fit procedure, for the muon channel on the...

  • Figure 6d

    Data from Figure 6 (middle right), located on page 15.

    10.17182/hepdata.95117.v1/t20

    Distribution of the multivariate discriminators, comparing data to simulation normalised after the fit procedure, for the muon channel on the...

  • Figure 6e

    Data from Figure 6 (lower left), located on page 15.

    10.17182/hepdata.95117.v1/t21

    Distribution of the multivariate discriminators, comparing data to simulation normalised after the fit procedure, for the muon channel on the...

  • Figure 6f

    Data from Figure 6 (lower right), located on page 15.

    10.17182/hepdata.95117.v1/t22

    Distribution of the multivariate discriminators, comparing data to simulation normalised after the fit procedure, for the muon channel on the...

  • Table 1

    Data from Table 1, located on page 5.

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    Values of the third-row elements of the CKM matrix inferred from low-energy measurements with the respective values of the top...

  • Table 2

    Data from Table 2, located on page 6.

    10.17182/hepdata.95117.v1/t24

    For each of the production and decay vertices, the cross section times branching fraction for the corresponding signal process from...

  • Table 4

    Data from Table 4, located on page 14.

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    The sources and relative values in percent of the systematic uncertainty in the measurement of the STb,b cross section. The...

  • The signal strengths obtained under SM assumptions.

    Data from Eq.6

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    The signal strengths obtained under SM assumptions.

  • Results obtained under SM assumptions.

    Data from Eq.8

    10.17182/hepdata.95117.v1/t27

    Results obtained under SM assumptions.

  • Results obtained under first BSM scenario.

    Data from Eq.10

    10.17182/hepdata.95117.v1/t28

    Results obtained under first BSM scenario.

  • Results obtained under second BSM scenario.

    Data from Eq.12

    10.17182/hepdata.95117.v1/t29

    Results obtained under second BSM scenario.

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