An Alternative Framework for E-Model Inflation in Supergravity

TL;DR

This paper introduces new realizations of E-model inflation in Supergravity using a pole in the kinetic term, with models predicting observable tensor-to-scalar ratios and spectral indices close to current measurements.

Contribution

It presents a novel framework for E-model inflation in Supergravity based on a kinetic pole, allowing for tuning-free models with realistic inflationary predictions.

Findings

For K=K1, inflation with N=2 predicts r≈0.001.

For K=~K1, models can achieve higher r and spectral index close to observations.

Tuning can be avoided in the ~K1 case, enabling more natural models.

Abstract

We present novel realizations of E-model inflation within Supergravity which are largely associated with the existence of a pole of order one in the kinetic term of the (gauge-singlet) inflaton superfield. This pole arises due to the selected logarithmic Kahler potentials K1 and ~K1, which parameterize the same hyperbolic manifold with scalar curvature R=-2/N, where N>0 is the coefficient of a logarithmic term. The associated superpotential W exhibits the same R charge with the inflaton-accompanying superfield and includes all the allowed renormalizable terms. For K=K1, inflation can be attained for N=2 at the cost of some tuning regarding the coefficients of the W terms and predicts a tensor-to-scalar ratio r at the level of 0.001. The tuning can be totally eluded for K=~K1, which allows for quadratic- and quartic-like models with N values increasing with r and spectral index ns close or even equal to its present central observational value.