CMS-HIG-17-010

CMS-HIG-17-010 ; CERN-EP-2017-207
Inclusive search for a highly boosted Higgs boson decaying to a bottom quark-antiquark pair
CMS Collaboration
16 September 2017
Phys. Rev. Lett. 120 (2018) 071802
Abstract: An inclusive search for the standard model Higgs boson (H) produced with large transverse momentum (${p_{\mathrm{T}}}$) and decaying to a bottom quark-antiquark pair ($\mathrm{b\bar{b}}$) is performed using a data set of ${\mathrm{p}}{\mathrm{p}}$ collisions at $\sqrt{s} = $ 13 TeV collected with the CMS experiment at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$. A highly Lorentz-boosted Higgs boson decaying to $\mathrm{b\bar{b}}$ is reconstructed as a single, large radius jet and is identified using jet substructure and dedicated b tagging techniques. The method is validated with $\mathrm{Z}\to\mathrm{b\bar{b}}$ decays. The $\mathrm{Z}\to\mathrm{b\bar{b}}$ process is observed for the first time in the single-jet topology with a local significance of 5.1 standard deviations (5.8 expected). For a Higgs boson mass of 125 GeV, an excess of events above the expected background is observed (expected) with a local significance of 1.5 (0.7) standard deviations. The measured cross section times branching fraction for production via gluon fusion of $\mathrm{H} \rightarrow \mathrm{b\bar{b}}$ with ${p_{\mathrm{T}}} > $ 450 GeV and in the pseudorapidity range $-2.5 < \eta < 2.5$ is 74 $\pm$ 48 (stat) $_{-{10} }^{+{17} }$ (syst) fb, which is consistent within uncertainties with the standard model prediction.
Links: e-print arXiv:1709.05543 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Data to simulation comparison of the $ {m_{\mathrm {SD}}} $ distribution for the leading jet, after the online selection and the jet $ {p_{\mathrm {T}}} > $ 450 GeV requirement. The QCD simulation is corrected by an overall factor of 0.78 to match the data yield.
png pdf	Figure 2: The $ {m_{\mathrm {SD}}} $ distributions in data for the failing (left) and passing (right) regions and combined $ {p_{\mathrm {T}}} $ categories. The QCD multijet background in the passing region is predicted using the failing region and the pass-fail ratio $R_{\mathrm {p}/\mathrm {f}}$. The features at 166 and 180 GeV in the $ {m_{\mathrm {SD}}} $ distribution are due to the kinematic selection on $\rho $, which affects each $ {p_{\mathrm {T}}} $ category differently. In the bottom panel, the ratio of the data to its statistical uncertainty, after subtracting the nonresonant backgrounds, is shown.
png pdf	Figure 2-a: The $ {m_{\mathrm {SD}}} $ distribution in data for the failing region and combined $ {p_{\mathrm {T}}} $ categories. The features at 166 and 180 GeV in the $ {m_{\mathrm {SD}}} $ distribution are due to the kinematic selection on $\rho $, which affects each $ {p_{\mathrm {T}}} $ category differently. In the bottom panel, the ratio of the data to its statistical uncertainty, after subtracting the nonresonant backgrounds, is shown.
png pdf	Figure 2-b: The $ {m_{\mathrm {SD}}} $ distribution in data for the passing region and combined $ {p_{\mathrm {T}}} $ categories. The QCD multijet background is predicted using the failing region and the pass-fail ratio $R_{\mathrm {p}/\mathrm {f}}$. The features at 166 and 180 GeV in the $ {m_{\mathrm {SD}}} $ distribution are due to the kinematic selection on $\rho $, which affects each $ {p_{\mathrm {T}}} $ category differently. In the bottom panel, the ratio of the data to its statistical uncertainty, after subtracting the nonresonant backgrounds, is shown.
png pdf	Figure 3: Profile likelihood test statistic $-2\Delta \log \mathcal {L}$ scan in data as a function of the Higgs and $\mathrm{Z} $ bosons signal strengths ($\mu _\mathrm{H}, \mu _\mathrm{Z} $).

Tables
png pdf	Table 1: Summary of the systematic uncertainties for signal and background. Dashes ($ {\text {--}} $) indicate that the uncertainty does not apply.
png pdf	Table 2: Fitted signal strength, expected and observed significance of the Higgs and $\mathrm{Z} $ boson signal. The 95% confidence level upper limit (UL) on the Higgs boson signal strength is also listed.

Summary

In summary, an inclusive search for the standard model Higgs boson with $p_{\mathrm{T}} > $ 450 GeV decaying to bottom quark-antiquark pairs and reconstructed as a single, large-radius jet is presented. The Z+jets process is observed for the first time in the single-jet topology with a significance of 5.1$\sigma$. The Higgs production is measured with an observed (expected) significance of 1.5$\sigma$ (0.7$\sigma$) when including Higgs boson $p_{\mathrm{T}}$ spectrum corrections accounting for higher-order and finite top quark mass effects. The measured cross section times branching fraction for the gluon fusion $\mathrm{H}(\mathrm{b\bar{b}})$ production for $p_{\mathrm{T}} > $ 450 GeV and $ | \eta | < $ 2.5 is 74 $\pm$ 48 (stat) $_{-10}^{+17}$ (syst) fb, which is consistent with the SM prediction within uncertainties.

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