  There is a general mechanism by which certain matter fields coupled to
gravity can generate a nontrivial effective potential for the conformal factor
of the metric. It is based on a nonstandard regularization method, with the
cutoff being defined independently of the conformal factor. This mechanism
produces a coupling of the matter fields to a dilaton, and a complicated
interaction between matter, dilaton and metric. When it is applied to the
standard model, it gives an effective potential which can be used to predict
the top and Higgs masses. If the purely gravitational contribution to the
potential is added, the mass of the dilaton is of the order of Planck's mass
and the large hierarchy between the Planck and Fermi scales appears to be due
to the smallness of the Higgs-dilaton coupling.
