Year: 2020
Type: article
Abstract: We consider Higgs inflation with an α R 2 term. It adds a new scalar degree of freedom, which leads to a two-field model of inflation. We do a complete slow-roll analysis of the three-dimensional parameter space of the R 2 coefficient α, the non-minimal coupling ξ and the Higgs self-coupling λ. We find three classes of inflationary solutions, but only pure R 2 and attractor solutions fit observations. We find that pure Higgs inflation is impossible when the R 2 term is present regardless of how small α is. However, we can have Higgs-like inflation, where the amplitude of the perturbations does not depend on α and the predictions as a function of e-folds are the same as in Higgs inflation, although the inflationary trajectory is curved in field space. The spectral index is 0.939 < n R < 0.967, and constraining it to the observed range, the tensor-to-scalar ratio varies from 3.8 × 10 −3 to the maximum allowed by observations, 0.079. Observational constraints on isocurvature perturbations contribute to these limits, whereas non-Gaussianity is automatically in the range allowed by observations.
Authors: Vera-Maria Enckell, Kari Enqvist, Syksy Räsänen, Lumi-Pyry Wahlman
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funder: Magnus Ehrnroothin Säätiö
OpenAlex ID: W2905221128