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| CMS-B2G-19-006 ; CERN-EP-2021-009 | ||
| Search for a heavy vector resonance decaying to a Z boson and a Higgs boson in proton-proton collisions at $\sqrt{s} = $ 13 TeV | ||
| CMS Collaboration | ||
| 16 February 2021 | ||
| Eur. Phys. J. C 81 (2021) 688 | ||
| Abstract: This paper describes the search for a heavy vector resonance decaying into a Z boson and the standard model Higgs boson, where the Z boson is identified through its leptonic decays to electrons, muons, or neutrinos, and the Higgs boson is identified through its hadronic decays. The search is performed in a Lorentz-boosted regime for resonances with masses larger than 800 GeV. The data samples of proton-proton collisions were collected from 2016 to 2018 at a center-of-mass energy of 13 TeV by the CMS experiment at CERN and correspond to an integrated luminosity of 137 fb$^{-1}$. Upper limits are derived on the production of a narrow heavy resonance Z' as a function of the Z' mass, and a mass below 3.5 and 3.7 TeV is excluded at 95% confidence level in models where the heavy vector boson couples exclusively to fermions and to bosons, respectively. These are the most stringent limits placed on the Heavy Vector Triplet Z' model to date. If the heavy vector boson couples exclusively to standard model bosons, upper limits on the product of the cross section and branching fraction are set between 23 and 0.3 fb for a Z' mass between 0.8 and 4.6 TeV, respectively. This is the first limit set on a heavy vector boson coupling exclusively to standard model bosons in its production and decay. | ||
| Links: e-print arXiv:2102.08198 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
The leading order Feynman diagrams of the heavy resonance Z' production through ${\mathrm{q} \mathrm{\bar{q}}}$ annihilation (left) and vector boson fusion (right), decaying to a Z boson (Z) and a Higgs boson (H). |
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Figure 1-a:
The leading order Feynman diagram of the heavy resonance Z' production through ${\mathrm{q} \mathrm{\bar{q}}}$ annihilation, decaying to a Z boson (Z) and a Higgs boson (H). |
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Figure 1-b:
The leading order Feynman diagram of the heavy resonance Z' production through vector boson fusion, decaying to a Z boson (Z) and a Higgs boson (H). |
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Figure 2:
The product of signal acceptance and efficiency in the 0$\ell $ (left column) and 2$\ell $ (right column) categories for the signal produced via ${\mathrm{q} \mathrm{\bar{q}}}$ annihilation (upper row) and vector boson fusion (lower row). |
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Figure 2-a:
The product of signal acceptance and efficiency in the 0$\ell $ category for the signal produced via ${\mathrm{q} \mathrm{\bar{q}}}$ annihilation. |
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Figure 2-b:
The product of signal acceptance and efficiency in the 2$\ell $ category for the signal produced via ${\mathrm{q} \mathrm{\bar{q}}}$ annihilation. |
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Figure 2-c:
The product of signal acceptance and efficiency in the 0$\ell $ category for the signal produced via vector boson fusion. |
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Figure 2-d:
The product of signal acceptance and efficiency in the 2$\ell $ category for the signal produced via vector boson fusion. |
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Figure 3:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the 2b tag (left column) and $\leq $1b tag (right column) non-VBF categories, for 0$\ell $ (upper row), 2e (middle row), and 2$\mu$ (lower row). The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 3-a:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the 2b tag non-VBF category, for 0$\ell$. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 3-b:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the $\leq $1b tag non-VBF category, for 0$\ell$. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 3-c:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the 2b tag non-VBF category, for 2e. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 3-d:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the $\leq $1b tag non-VBF category, for 2e. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 3-e:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the 2b tag non-VBF category, for 2$\mu$. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 3-f:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the $\leq $1b tag non-VBF category, for 2$\mu$. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 4:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the 2b tag (left column) and $\leq $1b tag (right column) VBF categories, for 0$\ell $ (upper row), 2e (middle row), and 2$\mu$ (lower row). The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 4-a:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the 2b tag tag VBF category, for 0$\ell $. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 4-b:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the $\leq $1b tag VBF category, for 0$\ell $. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 4-c:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the 2b tag tag VBF category, for 2e. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 4-d:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the $\leq $1b tag VBF category, for 2e. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 4-e:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the 2b tag tag VBF category, for 2$\mu$. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
png pdf |
Figure 4-f:
Fit to the ${m_{{j_{\mathrm{H}}}}}$ distribution in data in the $\leq $1b tag VBF category, for 2$\mu$. The shaded bands around the total background estimate represent the uncertainty from the fit to data in the jet mass SBs. The observed data are indicated by black markers. The observed data are indicated by black markers. The vertical shaded band indicates the VR region, which is blinded and not used in the fit to avoid potential contamination from VV resonant signals. The dashed vertical lines separate the LSB, VR, SR, and HSB. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 5:
Distributions in data in the 2b tag (left column) and $\leq $1b tag (right column) non-VBF categories, of ${m_{{\mathrm {X}}}^{\text {T}}}$ for 0$\ell $ (upper row), and ${m_{{\mathrm {X}}}}$ for 2e (middle row), and 2$\mu$ (lower row). The distributions are shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model B at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 5-a:
Distribution in data in the 2b tag tag non-VBF category, of ${m_{{\mathrm {X}}}^{\text {T}}}$ for 0$\ell $. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model B at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 5-b:
Distribution in data in the $\leq $1b tag non-VBF category, of ${m_{{\mathrm {X}}}^{\text {T}}}$ for 0$\ell $. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model B at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 5-c:
Distribution in data in the 2b tag tag non-VBF category, of ${m_{{\mathrm {X}}}}$ for 2e. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model B at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 5-d:
Distribution in data in the $\leq $1b tag non-VBF category, of ${m_{{\mathrm {X}}}}$ for 2e. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model B at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 5-e:
Distribution in data in the 2b tag tag non-VBF category, of${m_{{\mathrm {X}}}}$ for 2$\mu$. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model B at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 5-f:
Distribution in data in the $\leq $1b tag non-VBF category, of ${m_{{\mathrm {X}}}}$ for 2$\mu$. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model B at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 6:
Distributions in data in the 2b tag (left column) and $\leq $1b tag (right column) VBF categories, of ${m_{{\mathrm {X}}}^{\text {T}}}$ for 0$\ell $ (upper row), and ${m_{{\mathrm {X}}}}$ for 2e (middle row), and 2$\mu$ (lower row). The distributions are shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model C at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 6-a:
Distribution in data in the 2b tag tag VBF category, of ${m_{{\mathrm {X}}}^{\text {T}}}$ for 0$\ell $. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model C at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 6-b:
Distribution in data in the $\leq $1b tag VBF category, of ${m_{{\mathrm {X}}}^{\text {T}}}$ for 0$\ell $. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model C at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 6-c:
Distribution in data in the 2b tag tag VBF category, of ${m_{{\mathrm {X}}}}$ for 2e. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model C at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 6-d:
Distribution in data in the $\leq $1b tag VBF category, of ${m_{{\mathrm {X}}}}$ for 2e. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model C at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 6-e:
Distribution in data in the 2b tag tag VBF category, of ${m_{{\mathrm {X}}}}$ for 2$\mu$. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model C at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 6-f:
Distribution in data in the $\leq $1b tag VBF category, of ${m_{{\mathrm {X}}}}$ for 2$\mu$. The distribution is shown up to 4000 GeV, which corresponds to the event with the highest ${m_{{\mathrm {X}}}}$ or ${m_{{\mathrm {X}}}^{\text {T}}}$ observed in the SR. The shaded bands represent the uncertainty from the background estimation. The observed data are represented by black markers, and the potential contribution of a resonance produced in the context of the HVT model C at $ {m_{\mathrm{Z'}}} = $ 2000 GeV is shown as a dotted red line. The bottom panel shows $(N^{\text {data}}-N^{\text {bkg}})/\sigma $ for each bin, where $\sigma $ is the statistical uncertainty in data. |
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Figure 7:
Observed and expected 95% CL upper limit on $\sigma {\mathcal {B}}({\mathrm{Z'} \to \mathrm{Z} \mathrm{H}})$ with all categories combined, for the non-VBF signal (left) and VBF signal (right), including all statistical and systematic uncertainties. The inner green band and the outer yellow band indicate the regions containing 68 and 95%, respectively, of the distribution of expected limits under the background-only hypothesis. The solid curves and their shaded areas correspond to the product of the cross section and the branching fractions predicted by the HVT models A and B (left) and HVT model C (right), and their relative uncertainties. The CMS search for a heavy resonance using 2016 data and the same final state [14] is shown as a comparison. |
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Figure 7-a:
Observed and expected 95% CL upper limit on $\sigma {\mathcal {B}}({\mathrm{Z'} \to \mathrm{Z} \mathrm{H}})$ with all categories combined, for the non-VBF signal, including all statistical and systematic uncertainties. The inner green band and the outer yellow band indicate the regions containing 68 and 95%, respectively, of the distribution of expected limits under the background-only hypothesis. The solid curves and their shaded areas correspond to the product of the cross section and the branching fractions predicted by the HVT models A and B, and their relative uncertainties. The CMS search for a heavy resonance using 2016 data and the same final state [14] is shown as a comparison. |
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Figure 7-b:
Observed and expected 95% CL upper limit on $\sigma {\mathcal {B}}({\mathrm{Z'} \to \mathrm{Z} \mathrm{H}})$ with all categories combined, for the VBF signal, including all statistical and systematic uncertainties. The inner green band and the outer yellow band indicate the regions containing 68 and 95%, respectively, of the distribution of expected limits under the background-only hypothesis. The solid curves and their shaded areas correspond to the product of the cross section and the branching fractions predicted by the HVT models C, and their relative uncertainties. |
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Figure 8:
Observed exclusion limit in the space of the HVT model parameters [$ {g_\text {V}} {c_\text {H}} $, $g^2 {c_\text {F}} / {g_\text {V}} $], described in the text, for three different mass hypotheses of 2.0, 3.0, and 4.0 TeV for the non-VBF signal. The shaded bands indicate the side of each contour that is excluded. The benchmark scenarios corresponding to HVT models A and B are represented by a purple cross and a red point, respectively. The region of the parameter space where the natural resonance width ($\Gamma _{Z'}$) is larger than the typical experimental resolution of 4%, for which the narrow-width approximation is not valid, is shaded in grey. |
| Tables | |
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Table 1:
List of the 12 event categories used in the analysis. |
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Table 2:
Scale factors derived for the normalization of the ${\mathrm{t} \mathrm{\bar{t}}}$ and single top quark backgrounds for different event categories. Uncertainties due to the limited size of the event samples (stat.) and systematic effects (syst.) are reported as well. The scale factors of the 2e and 2$\mu$ categories are derived using the 1e1$\mu $ top quark control region as described in the text. |
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Table 3:
The expected and observed numbers of background events in the signal region for all event categories. The V+jets background uncertainties originate from the variation of the parameters within the fit uncertainties (fit) and the difference between the nominal and alternative function choice for the fit to ${m_{{j_{\mathrm{H}}}}}$ (alt). The ${\mathrm{t} \mathrm{\bar{t}}}$ and single top quark uncertainties arise from the ${m_{{j_{\mathrm{H}}}}}$ modeling, the statistical component of the top quark SF uncertainties, and the extrapolation uncertainty from the control region to the SR. The VV and VH normalization uncertainties come from the ${m_{{j_{\mathrm{H}}}}}$ modeling. |
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Table 4:
Summary of systematic uncertainties for the background and signal samples. The entries labeled with $\dagger $ are also propagated to the shapes of the distributions. Uncertainties marked with $\ddagger $ impact the signal cross section. Uncertainties in the same line are treated as correlated. All uncertainties except for in the integrated luminosity are considered correlated across the three years of data taking. |
| Summary |
| A search for a heavy resonance with a mass between 0.8 and 5.0 TeV, decaying to a Z boson and a Higgs boson, has been described. The data samples were collected by the CMS experiment in the period 2016-2018 at $\sqrt{s} = $ 13 TeV and correspond to an integrated luminosity of 137 fb$^{-1}$. In the final states explored the Z boson decays leptonically, resulting in events with either zero or two electrons or muons. Higgs bosons with a large Lorentz boost are reconstructed via their decays to hadrons. For models with a narrow spin-1 resonance, a new heavy vector boson Z' with mass below 3.5 and 3.7 TeV is excluded at 95% confidence level in models where the heavy vector boson couples predominantly to fermions and bosons, respectively. These are the most stringent limits placed on the Heavy Vector Triplet Z' model to date. If the heavy vector boson couples exclusively to standard model bosons, upper limits on the product of the cross section and branching fraction are set between 23 and 0.3 fb for a Z' mass between 0.8 and 4.6 TeV, respectively. This is the first limit set on a heavy vector boson coupling exclusively to standard model bosons in its production and decay. |
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