  We show that in a quadratic gravity based on Weyl's conformal geometry, the
Planck mass scale can be generated from quantum effects of the gravitational
field and the Weyl gauge field via the Coleman-Weinberg mechanism where a local
scale symmetry is broken. At the same time, the Weyl gauge field acquires a
mass less than the Planck mass by absorbing the scalar graviton. The shape of
the effective potential is almost flat owing to a gravitational character and
high symmetries, so our model would provide for an attractive model for the
inflationary universe. We also present a toy model showing spontaneous symmetry
breakdown of a global scale symmetry by moving from the Jordan frame to the
Einstein one, and point out its problems.

High Energy Physics - Theory;General Relativity and Quantum Cosmology;High Energy Physics - Phenomenology