  Following the thread of R. Gastmans, S. L. Wu and T. T. Wu, the calculation
in the unitary gauge for the $H \to \gamma \gamma$ process via one W loop is
repeated, but without the specific choice of the independent loop momentum for
the Feynman diagrams. This is based on the original 'Dyson scheme' provided in
Dyson's classical paper. I.e., the original integrations on all propagator
momenta are kept, not expressed by the specified independent loop momentum.
Correspondingly, the 4-dimension $\delta$ function at each vertex in which the
4-momentum conservation is embedded, is retained. Together with the Ward
identity of the W-W-photon vertex, the 4-momentum conservation of each vertex
guarantee the cancellation of all divergent integrals worse than logarithmic
without any uncertainty or ambiguity, with any shift of integrated momentum
eschewed. The calculation is in 4-dimension Minkowski phase space and without
any help of regularization. The resulting integrals are to the most
logarithmically divergent, hence is invariant for various setting of the
independent loop momentum and any of its shift. At last the logarithmically
divergent symmetric (tensor) integration is determined by the boundary
condition at infinity in momentum space inherent of the free Feynman
propagator, and the gauge (both $SU(2)\times U_Y(1)$ and $U_{em}(1)$) invariant
finite result can be obtained without the introduction of the 'Dyson
subtraction'. The physical boundary conditions at infinity of phase space can
make sense in many problems.
