A search for a fermiophobic Higgs boson in the di-photon final states is reported based on CDF data from 10.0 fb^-1 of integrated luminosity. In contrast with the Standard Model, the coupling of the Higgs boson to fermions is suppressed in fermiophobic models. Therefore, the diphoton decay mode can be greatly enhanced. In the presented note, no evidence of a resonance in the diphoton spectrum is observed, and upper limits are set on the cross section times branching fraction of the resonant state as a function of Higgs boson mass. We found an observed (expected) limit on the Fermiophobic Higgs boson production excluding Higgs bosons particles with a mass m_hf < 114 GeV (m_hf < 113 GeV) at the 95% confidence level.

For each channel, simulation of the diphoton mass spectrum for a Higgs boson with a mass of 115 GeV/c² decaying into two photons. The mass resolution of the diphoton channel is extremely good compared to dijet decay modes (Gaussian sigma / mean < 3%).

The invariant mass distribution is used as a discriminant for separating Higgs signal from the background. No significant narrow resonance is observed in the data. A smooth fit is made to the diphoton invariant mass distribution of the data using sidebands for each Higgs test mass and then interpolating to the signal region of that test mass. A Breit-Wigner function is added to the CP channels in order to model the Z boson contribution. The fit in the signal region is used to establish the background expectation. Example fits below are made from a Higgs test mass window of 115 GeV/c² with the corresponding data vs. fit residual also shown. Additional mass fits are shown in link below.

Obeserved and expected 95% C.L. upper limits on the production cross section and branching fraction and theory predictions for the fermiophobic benchmark Higgs boson model. A Bayesian binned likelihood approach was used.