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Authors
===============
Ray Culbertson 1
(rlc@fnal.gov)
Callie Demay 2
Craig Group 1
(group@fnal.gov)
Jamie Ray 3
(jamieray@fnal.gov)
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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:
AcceptanceTables_only_crop.ps
AcceptanceTables.tex
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:
DataFitsErrorBands.eps
Residuals.gif
Residuals.eps
The systematics that were considered for the limit setting are
shown in Table 1 below:
systematic_table_only_crop.ps
systematic_table.tex
Limits are set on the production cross section and branching
fraction using a Bayesian binned likelihood approach :
TPeaksHiggsLimits_zoom_27Oct08_3.0fb.eps
TPeaksHiggsLimits_zoom_br_27Oct08_3.0fb.eps
The limits in tabular form:
sigma_limit_table_only_crop.ps
sigma_limit_table.tex
*Plots blessed 10/23/08
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