2015/12/31 by Vincent Vennin, Kazuya Koyama, David Wands · 33 citations
Economics, Econometrics and Finance · Physics and Astronomy · #Cosmic background radiation #Cosmology and Gravitation Theories #Field (mathematics) #Galaxies: Formation, Evolution, Phenomena #Inflation (cosmology) #Inflaton #Planck #Quartic function #Scalar (mathematics) #Scalar field #Spectral index #Stochastic processes and financial applications #astro-ph.CO #hep-ph #hep-th
paper · pdf · doi:10.1088/1475-7516/2016/03/024
published in Journal of Cosmology and Astroparticle Physics 2016(03), 024 (Institute of Physics) · 18 pages without appendices (total 28 pages), 3 figures, 6 tables, matches the published version in JCAP (typo in last table of appendix E fixed)
openalex publication_date 2016/03/11 · openalex created_date 2016/06/24 · arxiv created 2017/09/12 · arxiv updated 2017/09/13 · openalex updated_date 2026/08/06
Bayesian inference techniques are used to investigate situations where an additional light scalar field is present during inflation and reheating. This includes (but is not limited to) curvaton-type models. We design a numerical pipeline where ≃ 200 inflaton setups × 10 reheating scenarios = 2000 models are implemented and we present the results for a few prototypical potentials. We find that single-field models are remarkably robust under the introduction of light scalar degrees of freedom. Models that are ruled out at the single-field level are not improved in general, because good values of the spectral index and the tensor-to-scalar ratio can only be obtained for very fine-tuned values of the extra field parameters and/or when large non-Gaussianities are produced. The only exception is quartic large-field inflation, so that the best models after Planck are of two kinds: plateau potentials, regardless of whether an extra field is added or not, and quartic large-field inflation with an extra light scalar field, in some specific reheating scenarios. Using Bayesian complexity, we also find that more parameters are constrained for the models we study than for their single-field versions. This is because the added parameters not only contribute to the reheating kinematics but also to the cosmological perturbations themselves, to which the added field contributes. The interplay between these two effects lead to a suppression of degeneracies that is responsible for having more constrained parameters.