Combination of searches for the Higgs boson using the full CDF data set

Abstract

We present a combination of searches for the standard model Higgs boson using the full CDF Run II data set, which corresponds to an integrated luminosity of 9.45--10.0 fb$^{-1}$ collected from $\sqrt{s}=1.96$ TeV $p{\bar{p}}$ collisions at the Fermilab Tevatron. The searches consider Higgs boson production from gluon-gluon fusion, vector-boson fusion, and associated production with either a $W$ or $Z$ boson or a $t{\bar{t}}$ pair. Depending on the production mode, Higgs boson decays to $W^+W^-$, $ZZ$, $b{\bar{b}}$, $\tau^+\tau^-$, and $\gamma\gamma$ are examined. We search for a Higgs boson with masses ($m_H$) in the range 90--200 GeV/$c^2$. In the absence of a signal, we expect based on combined search sensitivity to exclude at the 95% credibility level the mass regions $90<m_H<94$ GeV/$c^2$, $96<m_H<106$ GeV/$c^2$, and $153<m_H<175$ GeV/$c^2$. The observed exclusion regions are $90<m_H<102$ GeV/$c^2$ and $149<m_H<172$ GeV/$c^2$. A moderate excess of signal-like events relative to the background expectation at the level of 2.0 standard deviations is present in the data for the $m_H=125$ GeV/$c^2$ search hypothesis. We also present interpretations of the data within the context of a fermiophobic model and an alternative standard model incorporating a fourth generation of fermions. Finally, for the hypothesis of a new particle with mass 125 GeV/$c^2$, we constrain the coupling strengths of the new particle to $W^\pm$ bosons, $Z$ bosons, and fermions.