No-Scale Supergravity Realization of the Starobinsky Model of Inflation

TL;DR

A model for cosmological inflation based on a no-scale supergravity sector with an SU(2,1)/SU(2)×U(1) Kähler potential, a single modulus T, and an inflaton superfield Φ described by a Wess-Zumino model with superpotential parameters (μ, λ).

Abstract

We present a model for cosmological inflation based on a no-scale supergravity sector with an SU(2,1)/U(1) Kahler potential, a single modulus T and an inflaton superfield Phi described by a Wess-Zumino model with superpotential parameters (mu, lambda). This model yields a scalar spectral index n_s and a tensor-to-scalar ratio r that are compatible with the Planck measurements for values of lambda simeq mu/3M_P. For the specific choice lambda = mu/3M_P, the model is a no-scale supergravity realization of the R+R^2 Starobinsky model.

Figures (2)

• Figure 1: The potential $V$ in the NSWZ model for choices of $\lambda \sim \mu/3$ in Planck units, as indicated.
• Figure 2: Predictions from the NSWZ model for the tilt $n_s$ in the spectral index of scalar perturbations and for the tensor-to-scalar ratio $r$, compared with the 68 and 95% CL regions found in analyses of Planck and other data Planckinflation. In the main panel the lines are labelled by the values of $\lambda/\mu$ (in Planck units) assumed in each case. In the inset, the same cases are shown on a log scale to display better the values of $r$.