Warm DBI Inflation

TL;DR

This paper introduces a warm inflation model based on relativistic D-brane dynamics with a DBI kinetic term, incorporating thermal dissipation to address theoretical constraints and produce observable non-Gaussianity.

Contribution

It develops a warm DBI inflation framework that combines relativistic brane motion with thermal effects, reducing eta problem and allowing for significant non-Gaussianity.

Findings

Thermal dissipation alleviates eta problem.

Model predicts appreciable equilateral non-Gaussianity.

Large-field warm inflation can have small tensor-to-scalar ratio.

Abstract

We propose a warm inflationary model in the context of relativistic D-brane inflation in a warped throat, which has Dirac-Born-Infeld (DBI) kinetic term and is coupled to radiation through a dissipation term. The perturbation freezes at the sound horizon and the power spectrum is determined by a combination of the dissipative parameter and the sound speed parameter. The thermal dissipation ameliorates the {\it eta} problem and softens theoretical constraints from the extra-dimensional volume and from observational bounds on the tensor-to-scalar ratio. The warm DBI model can lead to appreciable non-Gaussianity of the equilateral type. As a phenomenological model, ignoring compactification constraints, we show that large-field warm inflation models do not necessarily yield a large tensor-to-scalar ratio.