Testing a Two Field Inflation Beyond the Slow-Roll Approximation

TL;DR

This paper explores a two-field inflation model beyond the slow-roll approximation, analyzing primordial perturbations and non-Gaussianity, and constrains the model using recent observational data, highlighting potential for observable non-Gaussian signals.

Contribution

It derives the potential form and perturbation spectrum for a two-field inflation model beyond slow-roll, including non-Gaussianity analysis and observational constraints.

Findings

Model is consistent with observations for certain DBI parameter ranges.

Large non-Gaussianity can be produced and may be observable in future experiments.

The framework extends inflation models beyond traditional slow-roll assumptions.

Abstract

We consider a model of two-field inflation, containing an ordinary scalar field and a DBI field. We work beyond the slow-roll approximation, but we assume a separable Hubble parameter. We then derive the form of potential in this framework and study the spectrum of the primordial perturbations in details. We also study the amplitude of the non-Gaussianity of the primordial perturbations both in equilateral and orthogonal configurations in this setup. We test the model with recent observational data and find some constraints on the model parameters. Our study shows that for some ranges of the DBI parameter, the model is consistent with observation and it is also possible to have large non-Gaussianity which would be observable by future improvements in experiments.