Search for Higgs Bosons Decaying into $b\overline{b}$ and Produced in Association with a Vector Boson in $p\overline{p}$ Collisions at $\sqrt{s}=1.8\mathrm{TeV}$

We present a new search for $H^{0}V$ production, where $H^0$ is a scalar Higgs boson decaying into $b\overline{b}$ with branching ratio $\beta$, and $V$ is a $Z^0$ boson decaying into $e^{+}{e}^{-}$, ${\mu }^{+}{\mu }^{-}$, or $\nu \overline{\nu }$. This search is then combined with previous searches for $H^{0}V$ where $V$ is a $W^{\pm }$ boson or a hadronically decaying $Z^0$. The data sample consists of $106\pm 4{\mathrm{pb}}^{-1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{TeV}$ accumulated by the Collider Detector at Fermilab. Observing no evidence of a signal, we set 95% Bayesian credibility level upper limits on $\sigma (p\overline{p}\to H^{0}V)\times \beta$. For $H^0$ masses of 90, 110, and $130\mathrm{GeV}/c^2$, the limits are 7.8, 7.2, and 6.6 pb, respectively.

Figure 1

Dijet invariant mass in $\nu \overline{\nu }b\overline{b}$ candidate events, for events with exactly one $b$-tagged jet and separately for events with two $b$-tagged jets. The single $b$-tag data include one overflow event.

Figure 2

Dijet invariant mass in ${\ell }^{+}{\ell }^{-}b\overline{b}$ candidate events. At least one jet is required to be $b$ tagged by the SVX algorithm.

Figure 3

Summary of all run I CDF 95% credibility level upper limits on $\sigma (p\overline{p}\to V{H}^0)·\beta$. The lines for the $\nu \overline{\nu }b\overline{b}$ and $\ell \nu b\overline{b}$ channels represent the combined limits from the single $b$-tagged and double $b$-tagged subsamples. Shown for comparison is the standard model prediction and the region excluded by the LEP experiments.