CMS-PAS-SUS-16-026

CMS-PAS-SUS-16-026
Search for electroweak production of charginos and neutralinos in the WH final state at 13 TeV
CMS Collaboration
August 2016

Abstract: A search is performed for beyond the standard model physics in events with a leptonically-decaying W boson, a Higgs boson decaying to a pair of b-quarks, and missing transverse energy, using 12.9 fb$^{-1}$ of 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 $\tilde{\chi}_{1}^{\pm} \rightarrow W \tilde{\chi}_{1}^{0}$ and $\tilde{\chi}_{2}^{0} \rightarrow H \tilde{\chi}_{1}^{0}$.
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ;

Figures & Tables	Summary	Additional Tables	References	CMS Publications

Additional information on efficiencies needed for reinterpretation of these results are available here.

Figures
png pdf	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.
png pdf	Figure 2-a: Distributions of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ (a), ${ {E_\mathrm {T}}^{\mathrm {miss}}}$ (b), ${M_{\mathrm {T}}}$ (c), 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.
png pdf	Figure 2-b: Distributions of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ (a), ${ {E_\mathrm {T}}^{\mathrm {miss}}}$ (b), ${M_{\mathrm {T}}}$ (c), 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.
png pdf	Figure 2-c: Distributions of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ (a), ${ {E_\mathrm {T}}^{\mathrm {miss}}}$ (b), ${M_{\mathrm {T}}}$ (c), 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.
png pdf	Figure 2-d: Distributions of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ (a), ${ {E_\mathrm {T}}^{\mathrm {miss}}}$ (b), ${M_{\mathrm {T}}}$ (c), 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.
png pdf	Figure 3-a: (a) Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ in ${\mathrm {CR}2\ell }$ after preselection requirements, comparing data to MC simulation. (b) Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ in ${\mathrm {CRMb}\bar{\mathrm {b}}}$ after preselection requirements.
png pdf	Figure 3-b: (a) Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ in ${\mathrm {CR}2\ell }$ after preselection requirements, comparing data to MC simulation. (b) Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ in ${\mathrm {CRMb}\bar{\mathrm {b}}}$ after preselection requirements.
png pdf	Figure 4: Distribution of ${M_{\mathrm {b}\bar{\mathrm {b}}}}$ after all signal region kinematic requirements. 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 $(m_{\tilde{\chi }_{1}^{\pm }}, m_{ {\tilde{\chi }_{1}^{0}}})$.
png pdf root	Figure 5: Expected and observed cross section limits at the 95% CL as a function of the chargino mass, where the LSP is assumed to have a mass of 1 GeV. The NLO theoretical cross section for production of $\tilde{\chi }_{1}^{\pm }\tilde{\chi }_{2}^{0}$ is also shown, assuming these are pure wino states.

Tables
png pdf	Table 1: Control region selections compared with the signal region.
png pdf	Table 2: Predicted and observed yields for ${\mathrm {CRMb}\bar{\mathrm {b}}}$ after the signal region requirements on ${E_{\mathrm {T}}^{\text {miss}}} $, ${M_{\mathrm {T}}}$, and ${M_{\mathrm {CT}}}$. The observed data yield is compared to the MC prediction for the dilepton top quark background after subtracting the predictions for the other (non-dilepton top quark) backgrounds. The uncertainties shown are statistical only, and the uncertainty on the ratio includes the statistical uncertainty on the data and MC samples.
png pdf	Table 3: Yields for ${\mathrm {CR}0\mathrm {b}}$, after all signal region requirements, including $ {M_{\mathrm {T}}}> $ 150 GeV. The observed data yield is compared to the W+light-jets MC prediction after subtracting the prediction for the other (non W+light-jets) backgrounds from the data yield. The uncertainties shown are statistical only, and the uncertainty on the ratio includes the statistical uncertainty on the data and MC samples.
png pdf	Table 4: Expected and observed yields in the signal region. The expected yields for some example signal points are also given. The uncertainties include both statistical and systematic sources.
png pdf	Table 5: 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 12.9 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 $\tilde{\chi}_{2}^{0}\to\mathrm{ H }{\tilde{\chi}_{1}^{0}}$.

Additional Tables

png pdf

Additional Table 1:
Cutflow yields for the signal $\mathrm{ pp \rightarrow \tilde{\chi }_{1}^{\pm } \tilde{\chi }_{2}^{0} }$ with the decays $\mathrm{ \tilde{\chi }_{1}^{\pm } \rightarrow W \tilde{\chi }_{1}^{0} }$ and $\mathrm{ \tilde{\chi }_{2}^{0} \rightarrow H \tilde{\chi }_{1}^{0} }$. The ``All events'' category below starts from all generated events where the W boson decays leptonically and the Higgs boson decays to a ${\mathrm{ b \bar{b} } } $ pair.

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