Dark Energy Properties in DBI Theory

TL;DR

This paper explores the properties of dark energy within the Dirac-Born-Infeld (DBI) framework, constraining model parameters with observations and analyzing unique features like zero sound speed attractors.

Contribution

It introduces generalized DBI models with multiple branes, expanding attractor solutions and highlighting novel signatures such as zero sound speed behavior.

Findings

Constraints on DBI model parameters from cosmological data

Identification of new attractor solutions including cosmological constant behavior

Detection of zero sound speed as a distinctive DBI signature

Abstract

The Dirac-Born-Infeld (DBI) action from string theory provides several new classes of dark energy behavior beyond quintessence due to its relativistic kinematics. We constrain parameters of natural potentials and brane tensions with cosmological observations as well as showing how to design these functions for a desired expansion history. We enlarge the attractor solutions, including new ways of obtaining cosmological constant behavior, to the case of generalized DBI theory with multiple branes. An interesting novel signature of DBI attractors is that the sound speed is driven to zero, unlike for quintessence where it is the speed of light.