Search for Higgs-like particle produced in association with $b$ quarks at CDF II

The CDF Collaboration

June 22, 2017

Abstract:

This note describes the search for a Higgs-like particle decaying into two $b$-quark jets produced in association with $b$-quark jets. We search for an enhancement in the invariant mass of the two $b$-quarks leading jets in triply $b$ tagged events. A limit on the cross section times the branching ratio into $b\bar{b}$ is set using a sample of $5.4$ fb$^{-1}$ of $p\bar p$ events collected with a dedicated on-line trigger path. The invariant mass shape of the dominant QCD background is parametrized using a data-driven technique, validated with the measurement of the $Z\rightarrow b\bar b$ cross section, reducing in this way the dependence of the analysis on simulation.

Plots

  SECVTX
Figure 1: Signal acceptance as function of the mass of the neutral scalar particle.

  • FIGURE1.PDF

      tagmass
    Figure 2: Tagmass distribution for $b$-, $c$- and light-jets as obtained with Monte Carlo simulation.

  • FIGURE2.PDF

      fit
    Figure 3: Invariant mass distribution of the two leading jets $m_{12}$ in the background templates.

  • FIGURE3.PDF

      fit
    Figure 4: Distribution of the flavor separator variable $x_{tag}$ in the background templates.

  • FIGURE4.PDF

      fit
    Figure 5: Invariant mass distribution of the two leading jets in the two positive and one negative tagged jets with the result of the fit projected into the $m_{12}$ variable.

  • FIGURE5.PDF

      fit
    Figure 6: Triple tagged events fit results projected into the invariant mass distribution $m_{12}$ under the background only hypothesis.

  • FIGURE6.PDF

      data-bkg
    Figure 7: Triple tagged events fit results projected into the flavor separator $x_{\text{tag}}$ variable under the background only hypothesis.

  • FIGURE7.PDF

      fiyt
    Figure 8: Result of the fit to the triple tagged data projected into the invariant mass $m_{12}$ variable. A signal component with a mass of the $\phi$ of 160 GeV/c$^2$ is added to the background templates.

  • FIGURE8.PDF

      daffbkg
    Figure 9: Result of the fit to the triple tagged data projected into the flavor separator $x_{\text{tag}}$ variable variable. A signal component with a mass of the $\phi$ of $160$ GeV/c$^2$ is added to the background templates.

  • FIGURE9.PDF

      fita
    Figure 10: The observed 95% C.L. upper limits on the cross section times the branching ratio. Linear scale on top, log scale on bottom.

  • FIGURE10.PDF

      dbkg
    Figure 11: The observed 95% C.L. upper limits on the cross section times the branching ratio. Linear scale on top, log scale on bottom.

  • FIGURE11.PDF

      kg
    Table 1: The yields as returned by the fit using background templates only to the triple tagged sample, compare to the predicted background counts.

  • TABLE1.PDF

      daewrkg
    Table 2: Summary of systematic uncertainties.

  • TABLE2.PDF

      datwerg
    Table 3: Median expected and observed limits on $\sigma \times \mathcal{B}r$, in pb.

  • TABLE3.PDF

    Emanuele Michielin