  We consider a Higgs mechanism in scale-invariant theories of gravitation. It
is shown that in spontaneous symmetry breakdown of scale invariance, gauge
symmetries are also broken spontaneously even without the Higgs potential if
the corresponding charged scalar fields couple to a scalar curvature in a
non-minimal way. In this gravity-inspired new Higgs mechanism, the non-minimal
coupling term, which is scale-invariant, plays a critical role. Various
generalizations of this mechanism are possible and particularly the
generalizations to non-abelian gauge groups and a scalar field with
multi-components are presented in some detail. Moreover, we apply our finding
to a scale-invariant extension of the standard model (SM) and calculate
radiative corrections. In particular, we elucidate the coupling between the
dilaton and the Higgs particle and show that the dilaton mass takes a value
around the GeV scale owing to quantum effects even if the dilaton is massless
at the classical level.
