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| CMS-PAS-EXO-19-007 | ||
| Search for dark photons in ZH decays at $\sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| May 2019 | ||
| Abstract: A search is presented for decays of a Higgs boson to an invisible particle together with an isolated photon, using the CMS experiment at the Large Hadron Collider. The Higgs boson is produced in association with a Z boson. The analysis is performed using a dataset recorded in 2016-18 corresponding to an integrated luminosity of 137.4 fb$^{-1}$, at a center-of-mass energy of 13 TeV. No significant excess of events above the standard model expectation is found, and the results are interpreted to place limits on the cross section times branching fraction of such decays of the Higgs boson. | ||
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Links:
CDS record (PDF) ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, JHEP 10 (2019) 139. The superseded preliminary plots can be found here. |
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| Figures | |
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Figure 1:
Feynman diagram for the $\mathrm{H} \to \gamma \gamma _D$ final state produced via ZH. |
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Figure 2:
The $ {m_{\mathrm {T}}} $ distributions for the e$\mu $, WZ, and ZZ control regions. Statistical and systematic uncertainties are shown. |
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Figure 2-a:
The $ {m_{\mathrm {T}}} $ distribution for the e$\mu $ control region. Statistical and systematic uncertainties are shown. |
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Figure 2-b:
The $ {m_{\mathrm {T}}} $ distribution for the WZ control region. Statistical and systematic uncertainties are shown. |
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Figure 2-c:
The $ {m_{\mathrm {T}}} $ distribution for the ZZ control region. Statistical and systematic uncertainties are shown. |
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Figure 3:
The $ {m_{\mathrm {T}}} $ distributions in the signal region for two Higgs boson mass values, backgrounds, and data for events with $|\eta ^\gamma | < $ 1 (left) and $|\eta ^\gamma | > $ 1 (right). The signal predictions correspond to $\mathrm {BR}(\mathrm{H} \to \text{invisible}+\gamma)=$ 10% assuming the SM ZH cross section for every given Higgs boson mass. The signal processes are stacked on top of all backgrounds. Statistical and systematic uncertainties are shown. |
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Figure 3-a:
The $ {m_{\mathrm {T}}} $ distributions in the signal region for two Higgs boson mass values, backgrounds, and data for events with $|\eta ^\gamma | < $ 1. The signal predictions correspond to $\mathrm {BR}(\mathrm{H} \to \text{invisible}+\gamma)=$ 10% assuming the SM ZH cross section for every given Higgs boson mass. The signal processes are stacked on top of all backgrounds. Statistical and systematic uncertainties are shown. |
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Figure 3-b:
The $ {m_{\mathrm {T}}} $ distributions in the signal region for two Higgs boson mass values, backgrounds, and data for events with $|\eta ^\gamma | > $ 1. The signal predictions correspond to $\mathrm {BR}(\mathrm{H} \to \text{invisible}+\gamma)=$ 10% assuming the SM ZH cross section for every given Higgs boson mass. The signal processes are stacked on top of all backgrounds. Statistical and systematic uncertainties are shown. |
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Figure 4:
Expected and observed 95% $ CL $ upper limits on $\sigma _{\mathrm{Z} \mathrm{H}} \times \mathrm {\cal B}(\mathrm{H} \to \text{invisible}+\gamma)$ as a function of $m_{\mathrm{H}}$. The expected $\sigma _{\mathrm{Z} \mathrm{H}}$ assuming $\mathrm {BR}(\mathrm{H} \to \text{invisible}+\gamma)=$10% for every given Higgs boson mass is also shown. |
| Tables | |
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Table 1:
Summary of the selection and the main background processes rejected by a given variable. |
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Table 2:
Observed yields, background estimates after the fit on data, and signal prediction in the signal region. The signal predictions correspond to $\mathrm {BR}(\mathrm{H} \to \text{invisible}+\gamma)=$10% assuming the SM ZH cross section for every given Higgs boson mass. The combinations of statistical and systematic uncertainties are reported. The values in brackets for the signal processes correspond to the total acceptance times selection efficiency for $\mathrm{Z} \to \ell \ell $ events, including electron, muon, and tau final states. |
| Summary |
| A search has been presented for a Higgs boson produced in association with a Z boson and decaying to an invisible particle together with an isolated photon, using the CMS experiment at the Large Hadron Collider. No significant excess of events is found. The results have been interpreted to place limits on the cross section times branching fraction of such decays of the Higgs boson. The analysis has been performed using a dataset recorded in 2016, 2017, and 2018, corresponding to an integrated luminosity of 137.4 fb$^{-1}$, at a center-of-mass energy of 13 TeV. The observed and expected 95% CL upper limits at $m_{\mathrm{H}} = $ 125 GeV assuming the SM production rate on $\mathrm{\cal B}(\mathrm{H} \to \mathrm{invisible}+\gamma)$ is 4.6% and 3.6%, respectively. |
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