Higgs-$R^2$ inflation -- full slow-roll study at tree-level
| Autor: | Enckell, Vera-Maria, Enqvist, Kari, Rasanen, Syksy, Wahlman, Lumi-Pyry |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | JCAP01(2020)041 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1088/1475-7516/2020/01/041 |
| Popis: | We consider Higgs inflation with an $\alpha R^2$ 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 $\alpha$, the non-minimal coupling $\xi$ and the Higgs self-coupling $\lambda$. 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 $\alpha$ is. However, we can have Higgs-like inflation, where the amplitude of the perturbations does not depend on $\alpha$ 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 $3.8\times10^{-3}$ 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. Comment: v2. Added references, corrected numerical analysis of inflationary trajectories. Range of values for the spectral index narrowed down. v3. Added references and clarified text, fixed typos. Published version. 18 pages, 5 figures |
| Databáze: | arXiv |
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