Abstract
Since the building-blocks of supersymmetric models include chiral superfields containing pairs of effective scalar fields, a two-field approach is particularly appropriate for models of inflation based on supergravity. In this paper, we generalize the two-field analysis of the inflationary power spectrum to supergravity models with arbitrary Kähler potential. We show how two-field effects in the context of no-scale supergravity can alter the model predictions for the scalar spectral index ns and the tensor-to-scalar ratio r, yielding results that interpolate between the Planck-friendly Starobinsky model and BICEP2-friendly predictions. In particular, we show that two-field effects in a chaotic no-scale inflation model with a quadratic potential are capable of reducing r to very small values ≪ 0.1. We also calculate the non-Gaussianity measure fNL, finding that is well below the current experimental sensitivity.
Highlights
The recent results from the Planck satellite [1] and the BICEP2 experiment [2] have inaugurated a new era in the confrontation of inflationary models with observation
We showed previously [26] that single-field models interpolating between BICEP2- friendly chaotic quadratic inflation and the Planck-friendly Starobinsky model could be obtained by varying θ in (57), keeping the stabilization coefficient c large, and we showed in Section 3.1 that two-field effects could interpolate between the quadratic and Starobinsky predictions even when θ = 0
We have presented in this paper a general formalism for the study of two-field effects in supergravity models
Summary
The recent results from the Planck satellite [1] and the BICEP2 experiment [2] have inaugurated a new era in the confrontation of inflationary models with observation. Another approach is to formulate more general frameworks that can accommodate a wider range of predictions compatible with the present observational range of r The latter was the point of view taken in [26], where it was shown how a class of simple no-scale supergravity models could interpolate between the prediction r ∼ 0.15 of chaotic inflation in a quadratic potential and the prediction r ∼ 0.003 of the Starobinsky model †. May enhance the magnitude of the scalar perturbations above the value expected naively from a single-field analysis, thereby suppressing the tensor-to-scalar ratio r This provides an independent way to interpolate between the limits of chaotic quadratic inflation and Starobinsky-like models that, as we verify, does not lead to large non-Gaussianities.
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