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| CMS-PAS-SUS-16-043 | ||
| Search for electroweak production of charginos and neutralinos in the WH final state in proton-proton collisions at $\sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| March 2017 | ||
| Abstract: A search is performed for physics beyond the standard model in events with a charged lepton (electron or muon), two jets identified as originating from a bottom quark decay, and significant imbalance in transverse energy, using 35.9 fb$^{-1}$ of proton-proton collision data recorded by CMS in 2016 at $\sqrt{s}= $ 13 TeV. This signature is predicted to occur, for example, in supersymmetric models from electroweak production of gauginos. The observed data are in agreement with the standard model prediction. The results are used to set cross section limits on chargino-neutralino production in a simplified model of supersymmetry with the decays $\tilde{\chi}_{1}^{\pm} \rightarrow \mathrm{W} \tilde{\chi}_{1}^{0}$ and $\tilde{\chi}_{2}^{0} \rightarrow \mathrm{H} \tilde{\chi}_{1}^{0}$. | ||
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Links:
CDS record (PDF) ;
inSPIRE record ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, JHEP 11 (2017) 029. The superseded preliminary plots can be found here. |
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| Figures & Tables | Summary | Additional Tables | References | CMS Publications |
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| Additional information on efficiencies needed for reinterpretation of these results are available here. Additional technical material for CMS speakers can be found here. |
| Figures | |
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Figure 1:
Feynman diagram of the SUSY simplified model targeted by this analysis: chargino-neutralino production with the chargino decaying to the W boson and the LSP, while the second neutralino decays to the Higgs boson and the LSP. |
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Figure 2:
Distributions of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ (top left), ${ {E_\mathrm {T}}^{\mathrm {miss}}}$ (top right), ${M_{\mathrm {T}}}$ (bottom left), and ${M_{\mathrm {CT}}}$ (bottom right) for signal and background events in simulation after the preselection. The ${ {E_\mathrm {T}}^{\mathrm {miss}}}$, ${M_{\mathrm {T}}}$, and ${M_{\mathrm {CT}}}$ distributions are shown after the 90 $ < {M_{\mathrm {b}\bar{\mathrm {b}}}}< $ 150 GeV requirement. Signal distributions are also overlaid as open histograms for various mass points. The legend entries for signal give the masses $(m_{\tilde{\chi }_{1}^{\pm }}, m_{ {\tilde{\chi }_{1}^{0}}})$ and the amount by which the signal cross section has been scaled for display purposes. |
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Figure 2-a:
Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ for signal and background events in simulation after the preselection. Signal distributions are also overlaid as open histograms for various mass points. The legend entries for signal give the masses $(m_{\tilde{\chi }_{1}^{\pm }}, m_{ {\tilde{\chi }_{1}^{0}}})$ and the amount by which the signal cross section has been scaled for display purposes. |
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Figure 2-b:
Distribution of ${ {E_\mathrm {T}}^{\mathrm {miss}}}$ for signal and background events in simulation after the preselection. The distribution is shown after the 90 $ < {M_{\mathrm {b}\bar{\mathrm {b}}}}< $ 150 GeV requirement. Signal distributions are also overlaid as open histograms for various mass points. The legend entries for signal give the masses $(m_{\tilde{\chi }_{1}^{\pm }}, m_{ {\tilde{\chi }_{1}^{0}}})$ and the amount by which the signal cross section has been scaled for display purposes. |
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Figure 2-c:
Distribution of ${M_{\mathrm {T}}}$ for signal and background events in simulation after the preselection. The distribution is shown after the 90 $ < {M_{\mathrm {b}\bar{\mathrm {b}}}}< $ 150 GeV requirement. Signal distributions are also overlaid as open histograms for various mass points. The legend entries for signal give the masses $(m_{\tilde{\chi }_{1}^{\pm }}, m_{ {\tilde{\chi }_{1}^{0}}})$ and the amount by which the signal cross section has been scaled for display purposes. |
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Figure 2-d:
Distribution of ${M_{\mathrm {CT}}}$ for signal and background events in simulation after the preselection. The distribution is shown after the 90 $ < {M_{\mathrm {b}\bar{\mathrm {b}}}}< $ 150 GeV requirement. Signal distributions are also overlaid as open histograms for various mass points. The legend entries for signal give the masses $(m_{\tilde{\chi }_{1}^{\pm }}, m_{ {\tilde{\chi }_{1}^{0}}})$ and the amount by which the signal cross section has been scaled for display purposes. |
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Figure 3:
(Left) Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ in ${\mathrm {CR}2\ell }$ after the selections in Table 1, comparing data to MC simulation. (Right) Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ in ${\mathrm {CRMb}\bar{\mathrm {b}}}$ after preselection requirements. The signal region range of 90 $ < {M_{\mathrm {b}\bar{\mathrm {b}}}} < $ 150 GeV has been removed from the plot. |
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Figure 3-a:
Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ in ${\mathrm {CR}2\ell }$ after the selections in Table 1, comparing data to MC simulation. |
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Figure 3-b:
Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ in ${\mathrm {CRMb}\bar{\mathrm {b}}}$ after preselection requirements. The signal region range of 90 $ < {M_{\mathrm {b}\bar{\mathrm {b}}}} < $ 150 GeV has been removed from the plot. |
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Figure 4:
Distribution of ${M_{\mathrm {T}}}$ in ${\mathrm {CR}0\mathrm {b}}$ after requiring the analysis preselection, the dijet mass window selection, and $ {M_{\mathrm {CT}}}> $ 170 GeV. |
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Figure 5:
Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ after all signal region kinematic requirements for the two exclusive ${ {E_\mathrm {T}}^{\mathrm {miss}}}$ bins. The left plot shows the bin with 125 $ < { {E_\mathrm {T}}^{\mathrm {miss}}}< $ 200 GeV, and the right plot shows $ { {E_\mathrm {T}}^{\mathrm {miss}}} > $ 200 GeV. The signal region corresponds to the bins with 90 $ < {M_{\mathrm {b}\bar{\mathrm {b}}}}< $ 150 GeV. The hatched band shows the total uncertainty on the background prediction, including statistical and systematic components. The signal distribution for a reference mass point is overlaid as an open histogram, and the legend entry for signal gives the masses $(m_{\tilde{\chi }_{1}^{\pm }}, m_{ {\tilde{\chi }_{1}^{0}}})$. |
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Figure 5-a:
Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ after all signal region kinematic requirements for the bin with 125 $ < { {E_\mathrm {T}}^{\mathrm {miss}}}< $ 200 GeV. The signal region corresponds to the bins with 90 $ < {M_{\mathrm {b}\bar{\mathrm {b}}}}< $ 150 GeV. The hatched band shows the total uncertainty on the background prediction, including statistical and systematic components. The signal distribution for a reference mass point is overlaid as an open histogram, and the legend entry for signal gives the masses $(m_{\tilde{\chi }_{1}^{\pm }}, m_{ {\tilde{\chi }_{1}^{0}}})$. |
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Figure 5-b:
Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ after all signal region kinematic requirements for $ { {E_\mathrm {T}}^{\mathrm {miss}}} > $ 200 GeV. The signal region corresponds to the bins with 90 $ < {M_{\mathrm {b}\bar{\mathrm {b}}}}< $ 150 GeV. The hatched band shows the total uncertainty on the background prediction, including statistical and systematic components. The signal distribution for a reference mass point is overlaid as an open histogram, and the legend entry for signal gives the masses $(m_{\tilde{\chi }_{1}^{\pm }}, m_{ {\tilde{\chi }_{1}^{0}}})$. |
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Figure 6:
Exclusion limits at the 95% CL for $\tilde{\chi }_{1}^{\pm }\tilde{\chi }_{2}^{0}\to \mathrm{ W } \mathrm{ H } {\tilde{\chi }_{1}^{0}} {\tilde{\chi }_{1}^{0}}$ in the plane of $m_{\tilde{\chi }_{1}^{\pm }}$ and $m_{ {\tilde{\chi }_{1}^{0}}}$. The area below the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1$\sigma _{\mathrm {experiment}}$ standard deviation uncertainties. The ${-1} \sigma _{\mathrm {experiment}}$ line does not appear as no mass points would be excluded in that case. The thin black lines show the effect of the theoretical uncertainties $\sigma _{\mathrm {theory}}$ on the signal cross section. |
| Tables | |
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Table 1:
Control region selections compared with the signal region. |
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Table 2:
Expected and observed yields in the signal regions using 35.9 fb$^{-1}$ data. The uncertainties shown include both statistical and systematic sources. Predicted yields are shown also for several signal models with the masses indicated and with only statistical uncertainties. |
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Table 3:
Sources of systematic uncertainty on the estimated signal yield along with their typical values. The ranges represent variation across the signal masses probed. |
| Summary |
| A search was performed for beyond the standard model physics in events with a leptonically-decaying W boson, a Higgs boson decaying to a $\mathrm{ b \bar{b} }$ pair, and $E_{\mathrm{T}}^{\text{miss}}$, using 35.9 fb$^{-1}$ of data recorded by CMS in 2016 at $\sqrt{s} = $ 13 TeV. The observed data are in agreement with the standard model expectation. The results were used to set cross section limits on chargino-neutralino production in a simplified SUSY model with the decays $\tilde{\chi}_{1}^{\pm} \to\mathrm{ W } \tilde{\chi}_{1}^{0}$ and $\tilde{\chi}_{2}^{0} \to\mathrm{ H } \tilde{\chi}_{1}^{0}$. We are able to probe $m_{\tilde{\chi}_{1}^{\pm}}$ values between 250 and 500 GeV when the ${\tilde{\chi}_{1}^{0}}$ is massless, and we probe $m_{\tilde{\chi}_{1}^{0}}$ values up to 120 GeV when $m_{\tilde{\chi}_{1}^{\pm}}$ is around 450 GeV. |
| Additional Tables | |
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Additional Table 1:
Cutflow of yields with 35.9 fb$^{-1}$ data for various signal model points, given as $(m_{\tilde{\chi }_{1}^{\pm }},m_{ {\tilde{\chi }_{1}^{0}}})$. The yields are normalized to the theoretical cross sections. The "All events'' category below starts from all generated events where the W boson decays leptonically and the Higgs boson decays to ${\mathrm{ b \bar{b} } } $. |
| For reinterpretations using both of the analysis signal bins, the correlation coefficient for the background prediction between the two bins is 0.61. |
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