Dynamically Induced Planck Scale and Inflation
Abstract
Theories where the Planck scale is dynamically generated from dimensionless interactions provide predictive inflationary potentials and super-Planckian field variations. We first study the minimal single-field realisation in the low-energy effective field theory limit, finding the predictions ns ≈ 0.96 for the spectral index and r ≈ 0.13 for the tensor-to-scalar ratio, which can be reduced down to ≈ 0.04 in presence of large couplings. Next we consider agravity as a dimensionless quantum gravity theory finding a multi-field inflation that converges towards an attractor trajectory that predicts ns≈ 0.96 and 0.003<r<0.13, interpolating between the quadratic and Starobinsky inflation. These theories relate the smallness of the weak scale to the smallness of inflationary perturbations: both arise naturally because of small couplings, implying a reheating temperature of 107-9 GeV. A measurement of r by Keck/Bicep3 would give us information on quantum gravity in the dimensionless scenario.