We explore the possibility that the fundamental theory of nature does not contain any scale. This implies a renormalizable quantum gravity theory where the graviton kinetic term has 4 derivatives, and can be reinterpreted as gravity minus an anti-graviton. We compute the super-Planckian RGE of adimensional gravity coupled to a generic matter sector. The Planck scale and a flat space can arise dynamically at quantum level provided that a quartic scalar coupling and its $\beta$ function vanish at the Planck scale. This is how the Higgs boson behaves for $M_h\approx 125$ GeV at $M_t\approx 171$ GeV. Within agravity, inflation is a generic phenomenon: the slow-roll parameters are given by the $\beta$-functions of the theory, and are small if couplings are perturbative. The predictions $n_s\approx 0.967$ and $r\approx 0.13$ arise if the inflaton is identified with the Higgs of gravity. Furthermore, quadratically divergent corrections to the Higgs mass vanish: a small weak scale is natural and can be generated by agravity quantum corrections.
A. Salvio and A. Strumia
Tue, 18 Mar 14