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 s√=1.96 TeV pp¯ 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 tt¯ pair. Depending on the production mode, Higgs boson decays to W+W−, ZZ, bb¯, τ+τ−, and γγ are examined. We search for a Higgs boson with masses (mH) in the range 90–200 GeV/c2. In the absence of a signal, we expect based on combined search sensitivity to exclude at the 95% credibility level the mass regions 90<mH<94 GeV/c2, 96<mH<106 GeV/c2, and 153<mH<175 GeV/c2. The observed exclusion regions are 90<mH<102 GeV/c2 and 149<mH<172 GeV/c2. 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 mH=125 GeV/c2 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/c2, we constrain the coupling strengths of the new particle to W± bosons, Z bosons, and fermions.