Search for the Standard Model Higgs Boson in $ZH\to {\ell }^{+}{\ell }^{-}b\overline{b}$ Production with the D0 Detector in $9.7{\mathrm{fb}}^{-1}$ of $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We present a search for the standard model (SM) Higgs boson produced in association with a $Z$ boson in $9.7{\mathrm{fb}}^{-1}$ of $p\overline{p}$ collisions collected with the D0 detector at the Fermilab Tevatron Collider at $\sqrt{s}=1.96\mathrm{TeV}$. Selected events contain one reconstructed $Z\to e^{+}{e}^{-}$ or $Z\to {\mu }^{+}{\mu }^{-}$ candidate and at least two jets, including at least one jet identified as likely to contain a $b$ quark. To validate the search procedure, we also measure the cross section for $ZZ$ production in the same final state. It is found to be consistent with its SM prediction. We set upper limits on the $ZH$ production cross section times branching ratio for $H\to b\overline{b}$ at the 95% C.L. for Higgs boson masses $90\le M_H\le 150\mathrm{GeV}$. The observed (expected) limit for $M_H=125\mathrm{GeV}$ is 7.1 (5.1) times the SM cross section.

Figure 1

Distributions of the global RF discriminant in the $t\overline{t}$ depleted region, assuming $M_H=125\mathrm{GeV}$, after the fit to the background-only model for the data (points with statistical error bars) and background (histograms) for (a) single-tagged events and (b) double-tagged events. (c) Background-subtracted distribution for (b). The signal distribution is shown with the SM cross section scaled by a factor of 5. The blue lines indicate the uncertainty from the fit.

Figure 2

Expected and observed 95% C.L. cross section upper limits on the $ZH$ cross section times branching ratio for $H\to b\overline{b}$, expressed as a ratio to the SM prediction.