Big rip in shift-symmetric Kinetic Gravity Braiding theories

TL;DR

This paper investigates the potential for a big rip singularity in shift-symmetric kinetic gravity braiding theories, showing that such models can lead to a future cosmic singularity instead of a de Sitter expansion.

Contribution

It demonstrates that shift-symmetric kinetic gravity braiding models can result in a big rip singularity, expanding the understanding of their possible cosmic futures.

Findings

Big rip singularity can be the sole future of certain models

Shift-symmetric models are not limited to de Sitter expansion

Explicit example of a big rip in these theories

Abstract

We revise the future fate of a group of scalar-tensor theories known as kinetic gravity braiding models. As it is well-known, these theories can safely drive the expansion of the universe towards a future de Sitter state if the corresponding Lagrangian is invariant under constant shifts in the scalar field. However, this is not the only possible future state of these shift-symmetric models as we show in this letter. In fact, future cosmic singularities characterized by a divergence of the energy density can also appear in this framework. We present an explicit example where a big rip singularity is the only possible future fate of the cosmos.