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CMS-B2G-20-002 ; CERN-EP-2022-001
Search for a W' boson decaying to a vector-like quark and a top or bottom quark in the all-jets final state at $\sqrt{s} = $ 13 TeV
JHEP 09 (2022) 088
Abstract: A search is presented for a heavy W' boson resonance decaying to a B or T vector-like quark and a t or a b quark, respectively. The analysis is performed using proton-proton collisions collected with the CMS detector at the LHC. The data correspond to an integrated luminosity of 138 fb$^{-1}$ at a center-of-mass energy of 13 TeV. Both decay channels result in a signature with a t quark, a Higgs or Z boson, and a b quark, each produced with a significant Lorentz boost. The all-hadronic decays of the Higgs or Z boson and of the t quark are selected using jet substructure techniques to reduce standard model backgrounds, resulting in a distinct three-jet W' boson decay signature. No significant deviation in data with respect to the standard model background prediction is observed. Upper limits are set at 95% confidence level on the product of the W' boson cross section and the final state branching fraction. A W' boson with a mass below 3.1 TeV is excluded, given the benchmark model assumption of democratic branching fractions. In addition, limits are set based on generalizations of these assumptions. These are the most sensitive limits to date for this final state.
Figures & Tables Summary Additional Figures References CMS Publications
Figures

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Figure 1:
Dominant Feynman diagrams for the signal model considered.

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Figure 1-a:
Dominant Feynman diagram for the signal model considered.

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Figure 1-b:
Dominant Feynman diagram for the signal model considered.

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Figure 2:
Simulated distributions of the discriminating variables for ${{\mathrm {t}\overline {\mathrm {t}}}}$, QCD, and ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ signal simulated events normalized to unity for the ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ analysis. Discriminant thresholds are shown as vertical dashed lines.

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Figure 2-a:
Simulated distribution of a discriminating variable for ${{\mathrm {t}\overline {\mathrm {t}}}}$, QCD, and ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ signal simulated events normalized to unity for the ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ analysis.

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Figure 2-b:
Simulated distribution of a discriminating variable for ${{\mathrm {t}\overline {\mathrm {t}}}}$, QCD, and ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ signal simulated events normalized to unity for the ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ analysis.

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Figure 2-c:
Simulated distribution of a discriminating variable for ${{\mathrm {t}\overline {\mathrm {t}}}}$, QCD, and ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ signal simulated events normalized to unity for the ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ analysis.

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Figure 2-d:
Simulated distribution of a discriminating variable for ${{\mathrm {t}\overline {\mathrm {t}}}}$, QCD, and ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ signal simulated events normalized to unity for the ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ analysis.

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Figure 3:
Simulated distributions of the discriminating variables for ${{\mathrm {t}\overline {\mathrm {t}}}}$, QCD, and ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ signal simulated events normalized to unity for the ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ analysis. Discriminant thresholds are shown as vertical dashed lines.

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Figure 3-a:
Simulated distribution of a discriminating variables for ${{\mathrm {t}\overline {\mathrm {t}}}}$, QCD, and ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ signal simulated events normalized to unity for the ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ analysis.

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Figure 3-b:
Simulated distribution of a discriminating variables for ${{\mathrm {t}\overline {\mathrm {t}}}}$, QCD, and ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ signal simulated events normalized to unity for the ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ analysis.

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Figure 3-c:
Simulated distribution of a discriminating variables for ${{\mathrm {t}\overline {\mathrm {t}}}}$, QCD, and ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ signal simulated events normalized to unity for the ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ analysis.

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Figure 3-d:
Simulated distribution of a discriminating variables for ${{\mathrm {t}\overline {\mathrm {t}}}}$, QCD, and ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ signal simulated events normalized to unity for the ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ analysis.

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Figure 4:
Diagram showing the regions used for background estimation. The signal region is C, the regions A and B are used to determine ${TF({p_{\mathrm {T}}}, \eta)}$, and F, K, and H are validation regions. The $x$ axis indicates the t tag category, and the $y$ axis represents the Higgs or Z boson tag category. The inverted, medium, and tight tag category definitions are given in Table 1.

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Figure 5:
Background closure test for the reconstructed W' boson invariant mass in region F (upper), K (middle), and H (lower) for the purpose of validation in the ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ (left) and ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ (right) analyses. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for three different W' mass hypotheses, assuming the medium VLQ mass, are shown as dotted histograms. The lower panel of each plot shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Figure 5-a:
Background closure test for the reconstructed W' boson invariant mass in region H, for the purpose of validation in the ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ analysis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for three different W' mass hypotheses, assuming the medium VLQ mass, are shown as dotted histograms. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Figure 5-b:
Background closure test for the reconstructed W' boson invariant mass in region F, for the purpose of validation in the ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ analysis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for three different W' mass hypotheses, assuming the medium VLQ mass, are shown as dotted histograms. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Figure 5-c:
Background closure test for the reconstructed W' boson invariant mass in region K, for the purpose of validation in the ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ analysis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for three different W' mass hypotheses, assuming the medium VLQ mass, are shown as dotted histograms. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Figure 5-d:
Background closure test for the reconstructed W' boson invariant mass in region K, for the purpose of validation in the ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ analysis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for three different W' mass hypotheses, assuming the medium VLQ mass, are shown as dotted histograms. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Figure 5-e:
Background closure test for the reconstructed W' boson invariant mass in region H, for the purpose of validation in the ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ analysis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for three different W' mass hypotheses, assuming the medium VLQ mass, are shown as dotted histograms. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Figure 5-f:
Background closure test for the reconstructed W' boson invariant mass in region F (upper), K (middle), and H (lower) for the purpose of validation in the ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ (left) and ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ (right) analyses. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for three different W' mass hypotheses, assuming the medium VLQ mass, are shown as dotted histograms. The lower panel of each plot shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Figure 6:
Reconstructed $m_{{\mathrm {W}'}}$ distributions (${m_{{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}}$ (upper), and ${m_{{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}}$ (lower)) in the signal region with estimated backgrounds and signal for several W' boson mass hypotheses at the medium VLQ mass, after a background-only fit. The combined statistical and systematic uncertainty in the total estimated background is indicated by the hatched region. The lower panels show the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Figure 6-a:
Reconstructed $m_{{\mathrm {W}'}}$ distributions (${m_{{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}}$) in the signal region with estimated backgrounds and signal for several W' boson mass hypotheses at the medium VLQ mass, after a background-only fit. The combined statistical and systematic uncertainty in the total estimated background is indicated by the hatched region. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Figure 6-b:
Reconstructed $m_{{\mathrm {W}'}}$ distributions (${m_{{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}}$) in the signal region with estimated backgrounds and signal for several W' boson mass hypotheses at the medium VLQ mass, after a background-only fit. The combined statistical and systematic uncertainty in the total estimated background is indicated by the hatched region. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Figure 7:
The W' boson 95% CL limits on the product of cross section and branching fraction. The expected (dashed) and observed (solid) limits, as well as the W' boson theoretical cross section, with its PDF and scale normalization uncertainties, are shown. The green (inner) and yellow (outer) bands indicate the 68% and 95% confidence intervals of the expected limit. The limits are given for the low (upper), medium (center), and high (lower) VLQ mass ranges.

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Figure 7-a:
The W' boson 95% CL limits on the product of cross section and branching fraction. The expected (dashed) and observed (solid) limits, as well as the W' boson theoretical cross section, with its PDF and scale normalization uncertainties, are shown. The green (inner) and yellow (outer) bands indicate the 68% and 95% confidence intervals of the expected limit. The limits are given for the low VLQ mass range.

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Figure 7-b:
The W' boson 95% CL limits on the product of cross section and branching fraction. The expected (dashed) and observed (solid) limits, as well as the W' boson theoretical cross section, with its PDF and scale normalization uncertainties, are shown. The green (inner) and yellow (outer) bands indicate the 68% and 95% confidence intervals of the expected limit. The limits are given for the medium VLQ mass range.

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Figure 7-c:
The W' boson 95% CL limits on the product of cross section and branching fraction. The expected (dashed) and observed (solid) limits, as well as the W' boson theoretical cross section, with its PDF and scale normalization uncertainties, are shown. The green (inner) and yellow (outer) bands indicate the 68% and 95% confidence intervals of the expected limit. The limits are given for the high VLQ mass range.

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Figure 8:
Expected (upper) and observed (lower) 95% CL limits for generalized hypotheses varying the fraction of tB (F(VLQ= B) and bT (F(VLQ= T)) from the W' decay (left), and the VLQ branching fraction to qH and qZ (right). The asterisk marker signifies the branching fractions for the benchmark model

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Figure 8-a:
Expected 95% CL limits for generalized hypotheses varying the fraction of tB (F(VLQ= B) and bT (F(VLQ= T)) from the W' decay. The asterisk marker signifies the branching fractions for the benchmark model

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Figure 8-b:
Expected 95% CL limits for generalized hypotheses varying the fraction of tB (F(VLQ= B) and bT (F(VLQ= T)) from the VLQ branching fraction to qH and qZ. The asterisk marker signifies the branching fractions for the benchmark model

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Figure 8-c:
Observed 95% CL limits for generalized hypotheses varying the fraction of tB (F(VLQ= B) and bT (F(VLQ= T)) from the W' decay. The asterisk marker signifies the branching fractions for the benchmark model

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Figure 8-d:
Observed 95% CL limits for generalized hypotheses varying the fraction of tB (F(VLQ= B) and bT (F(VLQ= T)) from the VLQ branching fraction to qH and qZ. The asterisk marker signifies the branching fractions for the benchmark model
Tables

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Table 1:
Selection regions used for signal identification and background estimation. The AK8 jet discriminant and mass selections are explicitly defined here for the t, Higgs, and Z jet tags.

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Table 2:
The signal efficiency (in percent) for the three VLQ mass ranges considered. The efficiency is given for the ${{\mathrm {t}} {\mathrm {H}} {\mathrm {b}}}$ and ${{\mathrm {t}} {\mathrm {Z}} {\mathrm {b}}}$ final states, separated into the low, medium, and high VLQ mass categories.

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Table 3:
Sources of systematic uncertainty that affect the final distributions. Sources that affect the normalization only are represented by a range of values for the systematic variation. Sources listing the systematic variation as ${\pm}1\sigma (x)$ affect the shape of the three-jet invariant mass distribution as well, which is dependent on $x$.
Summary
A search has been presented for a heavy W' boson decaying to a B or T vector-like quark and a t or b quark, respectively. The data correspond to an integrated luminosity of 138 fb$^{-1}$ collected between 2016 and 2018 with the CMS detector at the LHC in proton-proton collisions at $\sqrt{s} = $ 13 TeV. The signature considered for both decay modes is a t quark and a Higgs or Z boson, each decaying hadronically, and a b quark jet. Boosted heavy-resonance identification techniques are used to select the events containing three energetic jets and to suppress standard model backgrounds. No significant deviation from the standard model background prediction is observed. Upper limits are placed on the product of the W' boson cross section and the final state branching fraction as a function of the $m_{\mathrm{W'}}$. A W' boson with a mass below 3.1 TeV is excluded at 95% confidence level, given the benchmark model assumption of democratic branching fractions. In addition, limits are set based on generalizations of these assumptions. These are the most sensitive limits to date for this final state.
Additional Figures

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Additional Figure 1:
Background closure test for the reconstructed W' boson invariant mass in region F (upper), K (middle), and H (lower) for the purpose of validation in the tHb (left) and tZb (right) analyses given the low VLQ mass hypothesis.. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel of each plot shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 1-a:
Background closure test for the reconstructed W' boson invariant mass in region F for the purpose of validation in the tHb analysis given the low VLQ mass hypothesis.. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 1-b:
Background closure test for the reconstructed W' boson invariant mass in region F for the purpose of validation in the tZb analysis given the low VLQ mass hypothesis.. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 1-c:
Background closure test for the reconstructed W' boson invariant mass in region K for the purpose of validation in the tHb analysis given the low VLQ mass hypothesis.. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 1-d:
Background closure test for the reconstructed W' boson invariant mass in region K for the purpose of validation in the tZb analysis given the low VLQ mass hypothesis.. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 1-e:
Background closure test for the reconstructed W' boson invariant mass in region H for the purpose of validation in the tHb analysis given the low VLQ mass hypothesis.. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 1-f:
Background closure test for the reconstructed W' boson invariant mass in region H for the purpose of validation in the tZb analysis given the low VLQ mass hypothesis.. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 2:
Background closure test for the reconstructed W' boson invariant mass in region F (upper), K (middle), and H (lower) for the purpose of validation in the tHb (left) and tZb (right) analyses given the high VLQ mass hypothesis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel of each plot shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 2-a:
Background closure test for the reconstructed W' boson invariant mass in region F for the purpose of validation in the tHb analysis given the high VLQ mass hypothesis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 2-b:
Background closure test for the reconstructed W' boson invariant mass in region F for the purpose of validation in the tZb analysis given the high VLQ mass hypothesis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 2-c:
Background closure test for the reconstructed W' boson invariant mass in region K for the purpose of validation in the tHb analysis given the high VLQ mass hypothesis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 2-d:
Background closure test for the reconstructed W' boson invariant mass in region K for the purpose of validation in the tZb analysis given the high VLQ mass hypothesis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 2-e:
Background closure test for the reconstructed W' boson invariant mass in region H for the purpose of validation in the tHb analysis given the high VLQ mass hypothesis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 2-f:
Background closure test for the reconstructed W' boson invariant mass in region H for the purpose of validation in the tZb analysis given the high VLQ mass hypothesis. The data are shown as points with error bars and the estimated backgrounds as solid histograms after a background-only fit, with a hatched band indicating the uncertainty. Expected signals for for several W' boson mass hypotheses are shown. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 3:
Reconstructed $m_{\mathrm{W'}}$ distributions (${m_{\mathrm{t} \mathrm{H} \mathrm{b}}}$ (upper), and ${m_{\mathrm{t} \mathrm{Z} \mathrm{b}}}$ (lower)) in the signal region with estimated backgrounds and signal for several W' boson mass hypotheses, after a background-only fit given the low VLQ mass hypothesis. The combined statistical and systematic uncertainty in the total estimated background is indicated by the hatched region. The lower panels show the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 3-a:
Reconstructed $m_{\mathrm{W'}}$ distribution (${m_{\mathrm{t} \mathrm{H} \mathrm{b}}}$) in the signal region with estimated backgrounds and signal for several W' boson mass hypotheses, after a background-only fit given the low VLQ mass hypothesis. The combined statistical and systematic uncertainty in the total estimated background is indicated by the hatched region. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 3-b:
Reconstructed $m_{\mathrm{W'}}$ distribution (${m_{\mathrm{t} \mathrm{Z} \mathrm{b}}}$) in the signal region with estimated backgrounds and signal for several W' boson mass hypotheses, after a background-only fit given the low VLQ mass hypothesis. The combined statistical and systematic uncertainty in the total estimated background is indicated by the hatched region. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 4:
Reconstructed $m_{\mathrm{W'}}$ distributions (${m_{\mathrm{t} \mathrm{H} \mathrm{b}}}$ (upper), and ${m_{\mathrm{t} \mathrm{Z} \mathrm{b}}}$ (lower)) in the signal region with estimated backgrounds and signal for several W' boson mass hypotheses, after a background-only fit given the high VLQ mass hypothesis. The combined statistical and systematic uncertainty in the total estimated background is indicated by the hatched region. The lower panels show the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

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Additional Figure 4-a:
Reconstructed $m_{\mathrm{W'}}$ distribution (${m_{\mathrm{t} \mathrm{H} \mathrm{b}}}$) in the signal region with estimated backgrounds and signal for several W' boson mass hypotheses, after a background-only fit given the high VLQ mass hypothesis. The combined statistical and systematic uncertainty in the total estimated background is indicated by the hatched region. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.

png pdf
Additional Figure 4-b:
Reconstructed $m_{\mathrm{W'}}$ distribution (${m_{\mathrm{t} \mathrm{Z} \mathrm{b}}}$) in the signal region with estimated backgrounds and signal for several W' boson mass hypotheses, after a background-only fit given the high VLQ mass hypothesis. The combined statistical and systematic uncertainty in the total estimated background is indicated by the hatched region. The lower panel shows the difference between the number of events observed in the data and the predicted background, divided by the total uncertainty in the background and the statistical uncertainty in the data added in quadrature.
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