Dynamically induced Planck scale and inflation

Journal of High Energy Physics 2015.5 (2015): 065 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)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 multifield inflation that converges towards an attractor trajectory and 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 scenarioWe thank Juan García-Bellido, Mario Herrero-Valea and Hardi Veermae for useful discussions. This work was supported by grants PUT799, MTT8, MTT60, IUT23-6, CERN+,and by EU through the ERDF CoE program. The work of Alberto Salvio has been also supported by the Spanish Ministry of Economy and Competitiveness under grant FPA2012-32828, Consolider-CPAN (CSD2007-00042), the grant SEV-2012-0249 of the “Centro de Excelencia Severo Ochoa” Programme and the grant HEPHACOS-S2009/ESP1473 from the C.A. de Madri