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| CMS-EXO-20-005 ; CERN-EP-2020-173 | ||
| Search for dark photons in Higgs boson production via vector boson fusion in proton-proton collisions at $\sqrt{s} = $ 13 TeV | ||
| CMS Collaboration | ||
| 29 September 2020 | ||
| JHEP 03 (2021) 011 | ||
| Abstract: A search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS Collaboration at the LHC, using a data set corresponding to an integrated luminosity of 130 fb$^{-1}$, recorded at a center-of-mass energy of 13 TeV in 2016-2018. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for production via vector boson fusion and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a Higgs boson mass of 125 GeV, assuming the standard model production rates, the observed (expected) 95% confidence level upper limit on the branching fraction is 3.4 (2.7)%. This is the first search for such decays in the vector boson fusion channel. | ||
| Links: e-print arXiv:2009.14009 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ; | ||
| Figures & Tables | Summary | Additional Figures | References | CMS Publications |
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| Figures | |
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Figure 1:
A Feynman diagram for the VBF production of the $\mathrm{q} \mathrm{q} \mathrm{H} (\gamma \gamma _\mathrm {D})$ final state. |
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Figure 2:
The $ {m_{{\mathrm {j}} {\mathrm {j}}}} $ distributions from the simultaneous fit in the $ \gamma $+jets (upper left), $ {\mathrm{Z} (\ell \bar{\ell})+\gamma} $ (upper right), and $ {\mathrm{W} (\ell \nu)+\gamma} $ (lower) CRs. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The light green line, illustrating the possible contribution expected from inclusive SM Higgs boson production, assumes a branching fraction of 5% for $\mathrm{H} \to $ inv.+$\gamma $ decays. The lower panel in the figures shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Figure 2-a:
The $ {m_{{\mathrm {j}} {\mathrm {j}}}} $ distributions from the simultaneous fit in the $ \gamma $+jets CR. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The light green line, illustrating the possible contribution expected from inclusive SM Higgs boson production, assumes a branching fraction of 5% for $\mathrm{H} \to $ inv.+$\gamma $ decays. The lower panel shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Figure 2-b:
The $ {m_{{\mathrm {j}} {\mathrm {j}}}} $ distributions from the simultaneous fit in the $ {\mathrm{Z} (\ell \bar{\ell})+\gamma} $ CR. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The light green line, illustrating the possible contribution expected from inclusive SM Higgs boson production, assumes a branching fraction of 5% for $\mathrm{H} \to $ inv.+$\gamma $ decays. The lower panel shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Figure 2-c:
The $ {m_{{\mathrm {j}} {\mathrm {j}}}} $ distributions from the simultaneous fit in the $ {\mathrm{W} (\ell \nu)+\gamma} $ CR. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The light green line, illustrating the possible contribution expected from inclusive SM Higgs boson production, assumes a branching fraction of 5% for $\mathrm{H} \to $ inv.+$\gamma $ decays. The lower panel shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Figure 3:
The $ {m_{\mathrm {T}}} $ distributions from the simultaneous fit for events with $ {m_{{\mathrm {j}} {\mathrm {j}}}} < $ 1500 GeV in the $ {\mathrm{W} (\mathrm{e} \nu)}$+jets CRs (upper left), for events with $ {m_{{\mathrm {j}} {\mathrm {j}}}} \geq $ 1500 GeV in the $ {\mathrm{W} (\mathrm{e} \nu)}$+jets CRs (upper right), for events with $ {m_{{\mathrm {j}} {\mathrm {j}}}} < $ 1500 GeV in the SRs (lower left), and for events with $ {m_{{\mathrm {j}} {\mathrm {j}}}} \geq $ 1500 GeV in the SRs (lower right). The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The light green line, illustrating the possible contribution expected from inclusive SM Higgs boson production, assumes a branching fraction of 5% for $\mathrm{H} \to $ inv.+$\gamma $ decays. The lower panel in the figures shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Figure 3-a:
The $ {m_{\mathrm {T}}} $ distribution from the simultaneous fit for events with $ {m_{{\mathrm {j}} {\mathrm {j}}}} < $ 1500 GeV in the $ {\mathrm{W} (\mathrm{e} \nu)}$+jets CRs. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The light green line, illustrating the possible contribution expected from inclusive SM Higgs boson production, assumes a branching fraction of 5% for $\mathrm{H} \to $ inv.+$\gamma $ decays. The lower panel shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Figure 3-b:
The $ {m_{\mathrm {T}}} $ distribution from the simultaneous fit for events with $ {m_{{\mathrm {j}} {\mathrm {j}}}} \geq $ 1500 GeV in the $ {\mathrm{W} (\mathrm{e} \nu)}$+jets CRs. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The light green line, illustrating the possible contribution expected from inclusive SM Higgs boson production, assumes a branching fraction of 5% for $\mathrm{H} \to $ inv.+$\gamma $ decays. The lower panel shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Figure 3-c:
The $ {m_{\mathrm {T}}} $ distribution from the simultaneous fit for events with $ {m_{{\mathrm {j}} {\mathrm {j}}}} < $ 1500 GeV in the SRs. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The light green line, illustrating the possible contribution expected from inclusive SM Higgs boson production, assumes a branching fraction of 5% for $\mathrm{H} \to $ inv.+$\gamma $ decays. The lower panel shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Figure 3-d:
The $ {m_{\mathrm {T}}} $ distribution from the simultaneous fit for events with $ {m_{{\mathrm {j}} {\mathrm {j}}}} \geq $ 1500 GeV in the SRs. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The light green line, illustrating the possible contribution expected from inclusive SM Higgs boson production, assumes a branching fraction of 5% for $\mathrm{H} \to $ inv.+$\gamma $ decays. The lower panel shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Figure 4:
Expected and observed upper limits at 95% $ CL $ on the product of $ {\sigma _{\text {VBF}}} $ and $ \mathcal {B}(\mathrm{H} \to $ inv.+$\gamma) $ as a function of $m_{\mathrm{H}}$. The dot-dashed line shows the predicted signal corresponding to $0.05 {\sigma _{\text {VBF}}} $, assuming SM couplings. A linear interpolation is performed between the values obtained for the probed $m_{\mathrm{H}}$ values. |
| Tables | |
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Table 1:
Summary of the selection criteria in the SR, depending on the trigger path and data-taking year. Rows with a single entry indicate that the same requirement is applied for all data-taking years and trigger paths. |
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Table 2:
Summary of the $ {m_{\mathrm {T}}} $ binning choice in the SRs and CRs. |
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Table 3:
Summary of the uncertainties in the fitted signal cross section in fb for $m_{\mathrm{H}} = $ 125 GeV assuming the presence of a signal ($\sigma = $ 0.05$ {\sigma _{\text {SM}}} $) and the absence of a signal ($\sigma =$ 0). |
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Table 4:
Data, expected backgrounds, and estimated signal in the different regions. The expected background yields are shown with their best-fit normalizations from the simultaneous fit assuming background-only in the different regions. The combination of the statistical and systematic uncertainties is shown. The illustrative signal yield assumes a production cross section of 0.05$ {\sigma _{\text {SM}}} $. All data-taking periods and trigger paths are combined together for each region. |
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Table 5:
Observed and expected 95% CL limits at $m_{\mathrm{H}} = $ 125 GeV on $ \mathcal {B}(\mathrm{H} \to $ inv.+$\gamma) $ for the VBF category, $\mathrm{Z} \mathrm{H} $ category, and their combination. |
| Summary |
| A search has been presented for a Higgs boson that is produced via vector boson fusion (VBF) and that decays to an undetected particle and a photon. This is the first analysis for such decays in the VBF channel. The search has been performed by the CMS Collaboration using a data set corresponding to an integrated luminosity of 130 fb$^{-1}$ recorded at a center-of-mass energy of 13 TeV in 2016-2018. No significant excess of events above the expectation from the standard model background is found. The results are used to place limits on the product of the signal cross section ${\sigma_{\text{VBF}}} $ for VBF production and the branching fraction for such decays of the Higgs boson, in the context of a theoretical model where the undetected particle is a massless dark photon. Allowing for deviations from standard model VBF production, the upper limit on the product of ${\sigma_{\text{VBF}}} $ and $\mathcal{B}(\mathrm{H}\to $ inv$+\gamma) $ ranges from $\approx$160 to $\approx$2 fb, for $m_{\mathrm{H}}$ from 125 GeV to 1000 GeV. The observed (expected) upper limit at 95% confidence level at $m_{\mathrm{H}} = $ 125 GeV assuming standard model production rates on ${\mathcal{B}(\mathrm{H}\to\text{inv.}+\gamma)} $ is 3.4 (2.7)% for this channel. Combining with an existing analysis targeting associated Z boson production, and assuming the standard model rates, the observed (expected) upper limit at 95% confidence level at $m_{\mathrm{H}} = $ 125 GeV on ${\mathcal{B}(\mathrm{H}\to\text{inv.}+\gamma)} $ is 2.9 (2.1)%. |
| Additional Figures | |
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Additional Figure 1:
The $ {m_{{\mathrm {j}} {\mathrm {j}}}} $ distribution in the $ {{\mathrm {W}}({\mathrm {e}} {\nu})}$+jets control region. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The possible signal contamination is negligible. The lower panel in the figure shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Additional Figure 2:
The $ {m_{\mathrm {T}}} $ distribution in the $ {{\gamma} }$+jets control region. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The possible signal contamination is negligible. The lower panel in the figure shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Additional Figure 3:
The $ {m_{\mathrm {T}}} $ distribution in the $ {{\mathrm {Z}} ({\mu} ^+ {\mu} ^-)+ {\gamma}} $ control region. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The lower panel in the figure shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
png pdf |
Additional Figure 4:
The $ {m_{\mathrm {T}}} $ distribution in the $ {{\mathrm {W}}({\mu} {\nu})+ {\gamma}} $ control region. The category other background includes contributions from Z+jets, nonprompt, top quark, VV, and VVV processes. Overflow events are included in the last bin. The shaded bands represent the combination of the statistical and systematic uncertainties in the predicted yields. The lower panel in the figure shows a per-bin ratio of the data yield and the background expectation. The shaded band corresponds to the combined systematic and statistical uncertainty in the background expectation. |
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Compact Muon Solenoid LHC, CERN |
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