CMSPASB2G23008  
Search for a heavy resonance decaying into ZH in events with an energetic jet and two electrons, two muons, or missing transverse momentum  
CMS Collaboration  
26 March 2024  
Abstract: A search is presented for a heavy resonance decaying into a Z boson and a Higgs (H) boson. The analysis uses data from protonproton collisions at a centreofmass energy of 13 TeV corresponding to 138 fb$ ^{1} $ of integrated luminosity, recorded with the CMS experiment in the years 2016 to 2018. Resonance masses between 1.4 and 5 TeV are considered, resulting in large transverse momenta of the Z and H bosons. The search targets the Z boson decay into two electrons, two muons, or two neutrinos. The H boson is reconstructed with a single largeradius jet, recoiling against the Z boson. The search is designed for the hadronic H boson decay modes $ \mathrm{H} \to \mathrm{c}\bar{\mathrm{c}} $ and $ \mathrm{H} \to \mathrm{V}\mathrm{V}^{*} \to $ 4 quarks, where V denotes a W or Z boson. It achieves complementary sensitivity to previous searches targeting the $ \mathrm{H}\to \mathrm{b}\bar{\mathrm{b}} $ decays for high resonance masses.  
Links: CDS record (PDF) ; Physics Briefing ; CADI line (restricted) ; 
Figures  
png pdf 
Figure 1:
Distributions in $ m_{\mathrm{Z}^{\prime}}^{\text{rec}} $ for the dimuon (upper left), dielectron (upper right), and in $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ for the neutrino (lower) channels after the kinematic selections. The data are compared to simulation. The ratios to the total SM background are shown in the lower panels, where the statistical and total uncertainties are displayed as grey regions. The signal distributions are shown for an arbitrary cross section of 1 pb. 
png pdf 
Figure 1a:
Distributions in $ m_{\mathrm{Z}^{\prime}}^{\text{rec}} $ for the dimuon (upper left), dielectron (upper right), and in $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ for the neutrino (lower) channels after the kinematic selections. The data are compared to simulation. The ratios to the total SM background are shown in the lower panels, where the statistical and total uncertainties are displayed as grey regions. The signal distributions are shown for an arbitrary cross section of 1 pb. 
png pdf 
Figure 1b:
Distributions in $ m_{\mathrm{Z}^{\prime}}^{\text{rec}} $ for the dimuon (upper left), dielectron (upper right), and in $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ for the neutrino (lower) channels after the kinematic selections. The data are compared to simulation. The ratios to the total SM background are shown in the lower panels, where the statistical and total uncertainties are displayed as grey regions. The signal distributions are shown for an arbitrary cross section of 1 pb. 
png pdf 
Figure 1c:
Distributions in $ m_{\mathrm{Z}^{\prime}}^{\text{rec}} $ for the dimuon (upper left), dielectron (upper right), and in $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ for the neutrino (lower) channels after the kinematic selections. The data are compared to simulation. The ratios to the total SM background are shown in the lower panels, where the statistical and total uncertainties are displayed as grey regions. The signal distributions are shown for an arbitrary cross section of 1 pb. 
png pdf 
Figure 2:
The product of signal acceptance and efficiency for signal events as a function of $ m_{\mathrm{Z}^{\prime}} $ for the charged lepton and neutrino channels in the SR. The efficiency is calculated with respect to Z boson decays to neutrinos and to charged leptons for the neutrino and charged lepton channels, respectively. For comparison, the results from the $ \leq $1b category of the previous CMS search in the ZH channel [16] are shown as dashed lines. 
png pdf 
Figure 3:
Fits of the background functions to the $ m_{\mathrm{Z}^{\prime}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ distributions in data in the VRs (left) and simulation in the SRs (right) for the muon (upper), electron (middle), and neutrino (lower) channels. Each bin is divided by the bin width. The fit range excludes the kinematic turnon, created by the selection criteria. 
png pdf 
Figure 3a:
Fits of the background functions to the $ m_{\mathrm{Z}^{\prime}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ distributions in data in the VRs (left) and simulation in the SRs (right) for the muon (upper), electron (middle), and neutrino (lower) channels. Each bin is divided by the bin width. The fit range excludes the kinematic turnon, created by the selection criteria. 
png pdf 
Figure 3b:
Fits of the background functions to the $ m_{\mathrm{Z}^{\prime}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ distributions in data in the VRs (left) and simulation in the SRs (right) for the muon (upper), electron (middle), and neutrino (lower) channels. Each bin is divided by the bin width. The fit range excludes the kinematic turnon, created by the selection criteria. 
png pdf 
Figure 3c:
Fits of the background functions to the $ m_{\mathrm{Z}^{\prime}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ distributions in data in the VRs (left) and simulation in the SRs (right) for the muon (upper), electron (middle), and neutrino (lower) channels. Each bin is divided by the bin width. The fit range excludes the kinematic turnon, created by the selection criteria. 
png pdf 
Figure 3d:
Fits of the background functions to the $ m_{\mathrm{Z}^{\prime}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ distributions in data in the VRs (left) and simulation in the SRs (right) for the muon (upper), electron (middle), and neutrino (lower) channels. Each bin is divided by the bin width. The fit range excludes the kinematic turnon, created by the selection criteria. 
png pdf 
Figure 3e:
Fits of the background functions to the $ m_{\mathrm{Z}^{\prime}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ distributions in data in the VRs (left) and simulation in the SRs (right) for the muon (upper), electron (middle), and neutrino (lower) channels. Each bin is divided by the bin width. The fit range excludes the kinematic turnon, created by the selection criteria. 
png pdf 
Figure 3f:
Fits of the background functions to the $ m_{\mathrm{Z}^{\prime}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ distributions in data in the VRs (left) and simulation in the SRs (right) for the muon (upper), electron (middle), and neutrino (lower) channels. Each bin is divided by the bin width. The fit range excludes the kinematic turnon, created by the selection criteria. 
png pdf 
Figure 4:
Distributions in $ m_{\mathrm{Z}^{\prime}}^{\text{rec}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ for data in the SRs, together with fits of the background functions under the backgroundonly hypothesis for the muon (upper left), electron (upper right), and neutrino (lower) channels. The number of observed events in each bin is divided by the bin width. The signal predictions are shown for different $ \mathrm{Z}^{\prime} $ masses. 
png pdf 
Figure 4a:
Distributions in $ m_{\mathrm{Z}^{\prime}}^{\text{rec}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ for data in the SRs, together with fits of the background functions under the backgroundonly hypothesis for the muon (upper left), electron (upper right), and neutrino (lower) channels. The number of observed events in each bin is divided by the bin width. The signal predictions are shown for different $ \mathrm{Z}^{\prime} $ masses. 
png pdf 
Figure 4b:
Distributions in $ m_{\mathrm{Z}^{\prime}}^{\text{rec}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ for data in the SRs, together with fits of the background functions under the backgroundonly hypothesis for the muon (upper left), electron (upper right), and neutrino (lower) channels. The number of observed events in each bin is divided by the bin width. The signal predictions are shown for different $ \mathrm{Z}^{\prime} $ masses. 
png pdf 
Figure 4c:
Distributions in $ m_{\mathrm{Z}^{\prime}}^{\text{rec}} $ and $ m_{\mathrm{Z}^{\prime}}^{\mathrm{T}} $ for data in the SRs, together with fits of the background functions under the backgroundonly hypothesis for the muon (upper left), electron (upper right), and neutrino (lower) channels. The number of observed events in each bin is divided by the bin width. The signal predictions are shown for different $ \mathrm{Z}^{\prime} $ masses. 
png pdf 
Figure 5:
Expected and observed upper limits at 95% CL on the product of the production cross section $ \sigma\left(\mathrm{p}\mathrm{p} \to \mathrm{Z}^{\prime}\right) $ and the branching fraction $ \mathcal{B}\left(\mathrm{Z}^{\prime} \to \mathrm{Z}\mathrm{H}\right) $ as a function of the $ \mathrm{Z}^{\prime} $ mass. Expected limits obtained from the three different final states are compared to the combined result (left). The expected and observed limits from the combination of all final states are compared to predictions from the HVT and limits from a previous analysis [16] (right). 
png pdf 
Figure 5a:
Expected and observed upper limits at 95% CL on the product of the production cross section $ \sigma\left(\mathrm{p}\mathrm{p} \to \mathrm{Z}^{\prime}\right) $ and the branching fraction $ \mathcal{B}\left(\mathrm{Z}^{\prime} \to \mathrm{Z}\mathrm{H}\right) $ as a function of the $ \mathrm{Z}^{\prime} $ mass. Expected limits obtained from the three different final states are compared to the combined result (left). The expected and observed limits from the combination of all final states are compared to predictions from the HVT and limits from a previous analysis [16] (right). 
png pdf 
Figure 5b:
Expected and observed upper limits at 95% CL on the product of the production cross section $ \sigma\left(\mathrm{p}\mathrm{p} \to \mathrm{Z}^{\prime}\right) $ and the branching fraction $ \mathcal{B}\left(\mathrm{Z}^{\prime} \to \mathrm{Z}\mathrm{H}\right) $ as a function of the $ \mathrm{Z}^{\prime} $ mass. Expected limits obtained from the three different final states are compared to the combined result (left). The expected and observed limits from the combination of all final states are compared to predictions from the HVT and limits from a previous analysis [16] (right). 
png pdf 
Figure 6:
Observed upper limits at 95% CL on $ g_{\mathrm{F}} $ for different $ \mathrm{Z}^{\prime} $ masses as a function of the product of $ g_{\mathrm{H}} $ with the sign of $ g_{\mathrm{F}} $. The two benckmark scenarios of the HVT model are shown by the black markers. 
Tables  
png pdf 
Table 1:
Sources of systematic uncertainties considered in this analysis, and their effect on the signal normalisation. The uncertainty ranges correspond to different signal masses. 
Summary 
A search has been presented for the resonant production of a spin1 particle with mass in the range of 1.45 TeV and the decay into a Z and a Higgs (H) boson. The analysis is performed using data recorded with the CMS detector at a centreofmass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$ ^{1} $. The final states explored include the Z boson decays into a pair of electrons, muons or neutrinos, and the hadronic decays of the H boson reconstructed as a single largeradius jet. A novel approach analysing the flavour content and substructure of the H boson jet was deployed to improve the sensitivity for high resonance masses. This analysis shows for the first time the benefit of including H boson decays into $ \mathrm{c} \overline{\mathrm{c}} $ and $ \mathrm{V}\mathrm{V}^{*}\to\text{4 quarks} $, where V denotes a W or Z boson, besides the commonly used $ \mathrm{H}\to\mathrm{b}\overline{\mathrm{b}} $ decays in searches for new physics. Exclusion limits at 95% confidence level are set on both the mass of a heavy resonance and the couplings to fermions and bosons in the HVT model. Resonances with masses below 3 TeV are excluded. 
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