Phantom attractors in Kinetic Gravity Braiding theories: a dynamical system approach

TL;DR

This paper analyzes Kinetic Gravity Braiding theories using dynamical systems, revealing that besides de Sitter attractors, these models can also lead to future singularities like big rip scenarios.

Contribution

It demonstrates the existence of diverse future attractors, including singularities, in shift-symmetric Kinetic Gravity Braiding models through a dynamical system approach.

Findings

Future singularities can occur in Kinetic Gravity Braiding theories.

Explicit examples show big rip as a possible future attractor.

De Sitter states are not the only asymptotic solutions.

Abstract

We revise the expansion history of the scalar field theories known as Kinetic Gravity Braiding. These theories are well-known for the possibility of driving the expansion of the cosmos towards a future self-tuning de Sitter state when the corresponding Lagrangian is invariant under constant shifts in the scalar field. Nevertheless, this is not the only possible future fate of these shift-symmetric models. Using a dynamical system formulation we show that future cosmological singularities can also appear in this framework. Moreover, we present explicit examples where the future attractor in the configuration space of the theory corresponds to a big rip singularity.