  A search for a narrow Higgs boson resonance in the diphoton mass spectrum is
presented based on data corresponding to 10 fb-1 of integrated luminosity from
proton-antiproton collisions at \surds = 1.96 TeV collected by the CDF
experiment. In addition to searching for a resonance in the diphoton mass
spectrum, we employ a multivariate discriminant technique for the first time in
this channel at CDF. No evidence of signal is observed, and upper limits are
set on the cross section times branching ratio of the resonant state as a
function of Higgs boson mass. The limits are interpreted in the context of the
standard model with an expected (observed) limit on the cross section times
branching ratio of 9.9 (17.0) times the standard model prediction at the 95%
credibility level for a Higgs boson mass of 125 GeV/c2. Moreover, a Higgs boson
with suppressed couplings to fermions is excluded for masses below 114 GeV/c2
at the 95% credibility level.
