  We generalize the scale invariant gravity by allowing a negative kinetic
energy term for the classical scalar field. This gives birth to a new
scalar-tensor theory of gravity, in which the scalar field is in fact an
auxiliary field. For a pure gravity theory without matter, the scale symmetric
phase represents an equivalent class of gravity theories, which the Einstein
gravity plus a cosmological constant belongs to under a special gauge choice.
The one-loop quantum correction of the theory is calculated by using the
Vilkovisky-DeWitt's method. We find that the scale symmetry is broken
dynamically, and that the Einstein gravity is the ground state of the broken
phase. We also briefly discuss the consequent cosmological implications. It is
shown that the time-delay experiment restricts the present universe to be very
close to the ground state.
