Towards a reliable effective field theory of inflation Bastero Gil, Mar Berera, Arjun Ramos, Rudnei O. Rosa, João G. We present the first quantum field theory model of inflation that is renormalizable in the matter sector, with a super-Hubble inflaton mass and sub-Planckian field excursions, which is thus technically natural and consistent with a high-energy completion within a theory of quantum gravity. This is done in the framework of warm inflation, where we show, for the first time, that strong dissipation can fully sustain a slow-roll trajectory with slow-roll parameters larger than unity in a way that is both theoretically and observationally consistent. The inflaton field corresponds to the relative phase between two complex scalar fields that collectively break a U(1)gauge symmetry, and dissipates its energy into scalar degrees of freedom in the warm cosmic heat bath. A discrete interchange symmetry protects the inflaton mass from large thermal corrections. We further show that the dissipation coefficient decreases with temperature in certain parametric regimes, which prevents a large growth of thermal inflaton fluctuations. We find, in particular, a very good agreement with the Planck legacy data for a simple quadratic inflaton potential, predicting a low tensor-to-scalar ratio r 10−5. 2021-03-15T11:33:15Z 2021-03-15T11:33:15Z 2020-12-29 info:eu-repo/semantics/article Bastero-Gil, M., Berera, A., Ramos, R. O., & Rosa, J. G. (2020). Towards a reliable effective field theory of inflation. Physics Letters B, 136055. [https://doi.org/10.1016/j.physletb.2020.136055] http://hdl.handle.net/10481/67227 10.1016/j.physletb.2020.136055 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License Atribución 3.0 España Elsevier