Search for a Fermiophobic Higgs Boson with the Diphoton Final State at CDF




Ray Culbertson 1

Callie Demay 2

Craig Group 1

Jamie Ray 3

A search for the Higgs boson in the diphoton decay channel is reported. The Standard Model branching fraction is small, but other models - such as fermiophobic models where the Higgs does not couple to fermions - predict much larger branching fractions for the diphoton decay. Here, a study is reported which used CDF data to ls place the strongest limit to date by a hadron collider on models of this type. The results are based on 3.0 fb-1 of CDF Run II data which were approved by the CDF collaboration on 10/23/08.

Public Note

  • Simulation of the diphoton mass spectrum for a Higgs boson with a mass of 110 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 % ). Note that this analysis roughly doubles signal acceptance by including a channel with one forward photon (compared to an analysis with only central photons).



  • In associated production with a vector boson and vector boson fusion (VBF) production mechanisms the diphoton pT spectrum for Higgs boson signal events is much harder than the spectrum from standard model diphoton and QCD events containing fake photons. A cut on this variable of 75 GeV/c was found to be optimal based on expected sensitivity.



  • Signal acceptance, in percent, for each signal process and mass point generated after applying the pTgg >75 GeV/c cut are given in the Table below:

  • No significant narrow resonance is observed in the data. The diphoton data is fit to a smooth distribution using mass sidebands for each Higgs test mass to establish the background expectation:


  • The systematics that were considered for the limit setting are shown in Table 1 below:

  • Limits are set on the production cross section and branching fraction using a Bayesian binned likelihood approach :



  • The limits in tabular form:

  • *Plots blessed 10/23/08

    Page prepared by Craig Group ( 10/24/08