Inhomogeneous Reheating Scenario with DBI fields

TL;DR

This paper introduces a new inhomogeneous reheating mechanism involving DBI fields, showing how they generate primordial density perturbations with specific non-Gaussian features, and explores its implications and connections to other models.

Contribution

It presents a generalized framework for curvature perturbation and non-Gaussianity in the inhomogeneous DBI reheating scenario, highlighting the role of sound speed and decay processes.

Findings

Curvature perturbation depends on decay process and sound speed c_s.

Non-Gaussianity parameter f_NL is independent of c_s.

Certain decay processes produce detectable non-Gaussianity.

Abstract

We discuss a new mechanism which can be responsible for the origin of the primordial perturbation in inflationary models, the inhomogeneous DBI reheating scenario. Light DBI fields fluctuate during inflation, and finally create the density perturbations through modulation of the inflation decay rate. In this note, we investigate the curvature perturbation and its non-Gaussianity from this new mechanism. Presenting generalized expressions for them, we show that the curvature perturbation not only depends on the particular process of decay but is also dependent on the sound speed $c_s$ from the DBI action. More interestingly we find that the non-Gaussianity parameter $f_{NL}$ is independent of $c_s$. As an application we exemplify some decay processes which give a viable and detectable non-Gaussianity. Finally we find a possible connection between our model and the DBI-Curvaton mechanism.