Dirac-Born-Infeld warm inflation realization in the strong dissipation regime

Meysam Motaharfar,Rudnei O Ramos

doi:10.1103/physrevd.104.043522

Abstract

We consider warm inflation with a Dirac-Born-Infeld (DBI) kinetic term in which both the nonequilibrium dissipative particle production and the sound speed parameter slow the motion of the inflaton field. We find that a low sound speed parameter removes, or at least strongly suppresses, the growing function appearing in the scalar of curvature power spectrum of warm inflation, which appears due to the temperature dependence in the dissipation coefficient. As a consequence of that, a low sound speed helps to push warm inflation into the strong dissipation regime, which is an attractive regime from a model building and phenomenological perspective. In turn, the strong dissipation regime of warm inflation softens the microscopic theoretical constraints on cold DBI inflation. The present findings, along with the recent results from swampland criteria, give a strong hint that warm inflation may consistently be embedded into string theory.

Highlights

Warm inflation (WI) [1,2,3] is an alternative dynamical realization for conventional cold inflation (CI) [4,5,6,7,8] during which the inflaton field dissipates its vacuum energy into an ambient radiation bath, eliminating the necessity of a postinflationary reheating process [9] and leading into different possibilities for a graceful exit mechanism [10]
We find that a low sound speed parameter removes, or at least strongly suppresses, the growing function appearing in the scalar of curvature power spectrum of warm inflation, which appears due to the temperature dependence in the dissipation coefficient
We studied the effects of a low sound speed on the dynamics of perturbations equations of WI inspired by string motivated models that include relativistic D-brane motion

Summary

Introduction

Warm inflation (WI) [1,2,3] is an alternative dynamical realization for conventional cold inflation (CI) [4,5,6,7,8] during which the inflaton field dissipates its vacuum energy into an ambient radiation bath, eliminating the necessity of a postinflationary reheating process [9] and leading into different possibilities for a graceful exit mechanism [10] Such a nonequilibrium dissipative particle production process acts to slow the motion of the inflaton field, allowing the embedding of steeper potentials in the WI context and helping to solve, for example, the so-called η-problem [11,12,13].

Objectives

Results

Conclusion