Planck and Electroweak Scales Emerging from Conformal Gravity

We show that both the Planck and electroweak mass scales can be generated from conformal gravity via the Coleman–Weinberg mechanism of dimensional transmutation. At the first step, the Planck scale is generated via the Coleman–Weinberg mechanism in the sector of conformal gravity, which means that radiative corrections associated with gravitons induce spontaneous symmetry breakdown of a local conformal symmetry. At the second step, the vacuum expectation value of a scalar field is transmitted to the sector of the standard model via a potential involving the conformally invariant part and the contribution from the Coleman–Weinberg mechanism, thereby generating the electroweak scale. The huge hierarchy between the two scales can be explained in terms of a very tiny coupling constant between the scalar and the Higgs field in a consistent way.