A search for the SM Higgs boson in the diphoton decay channel is reported
using 7.0 fb-1 of data. The previous result used central
photons (|&eta|<1.1) collected from standard CDF photon selection.
Here, we improve this identification by incorporating a new photon
selection that uses a neural network to reject jet backgrounds.
Sensitivity is also greatly improved by the addition of forward (1.2<|&eta|<2.8)
photons and the development of a new algorithm which selects photons that have
converted into an electron-positron pair. No significant excess over the background
was observed, so we present 95% C.L. upper limits on the production cross section
times H&rarr&gamma&gamma branching fraction relative to the SM expectation. For Higgs masses between
100 and 150 GeV/c2 the expected limits range from 13.0 to 27.2 and observed limits range
from 8.2 to 28.2. This is an approximate 33% improvement from the previous result
using 5.4 fb-1.