The Dark Energy Properties of the Dirac–Born–Infeld Action

Xinyou Zhang,Qing Zhang,Yongchang Huang

doi:10.3390/e14071203

Abstract

Introducing a new potential, we deduce a general Lagrangian for Dirac–Born– Infeld (DBI) inflation, in which the determinant of the induced metric naturally includes the kinetic energy and the potential energy. In particular, the potential energy and kinetic energy can convert into each other at any same order, which is in agreement with the limit of classical physics. We also present a general sound speed in the evolutions of the universe, and the exact expressions of energy-momentum tensor, pressure and density. Furthermore, from the results we obtain the new equation of states. The analytic form of the action that is consistent with data turns out to be surprisingly simple and easy to categorize. Finally, we examine properties of the dark energy and introduce a novel mechanism for realizing either quintessence or phantom dark energy dominated phases within a string theoretical context.

Highlights

High energy physics theories for dark energy leading the accelerated expansion of the Universe face issues of naturalness
We find a natural way to guarantee the potential energy in the Dirac–Born– Infeld (DBI) Lagrangian could convert into kinetic energy in any same order, and improve the work in [43,44,45,46,47]
In our previous work [48], we show that the Taylor expansion of the DBI action can be reduced into the form in the non-linear classical physics

Summary

Introduction

High energy physics theories for dark energy leading the accelerated expansion of the Universe face issues of naturalness. DBI inflation has the additional nice feature of a natural ending when the branes collide, where the collision itself is useful for reheating and the possible production of cosmic strings String theory dictates both the dynamics of the inflation and its potential, so that one can make precise cosmological predictions from a given set of background parameters [24]. Even if the problem is solved in flux compactification, one still must engineer a flat interbrane potential to satisfy the standard slow-roll conditions In this case, we find a natural way to guarantee the potential energy in the DBI Lagrangian could convert into kinetic energy in any same order, and improve the work in [43,44,45,46,47]. We have introduced a novel mechanism for realizing either quintessence or phantom dark energy dominated phases within a string theoretical context

The New General Lagrangian of DBI Inflation

Energy-Momentum Tensor and Sound Speed of the New DBI Action

Dark Energy with DBI Inflation

Discussion and Conclusion