DBI Genesis: An Improved Violation of the Null Energy Condition

TL;DR

This paper demonstrates that DBI conformal galileons can stably violate the Null Energy Condition while maintaining stability, subluminal propagation, and a consistent Lorentz-invariant vacuum, offering a novel theoretical framework.

Contribution

It introduces a new stable NEC-violating background within DBI conformal galileons that preserves Poincare invariance and has a well-defined S-matrix, unlike previous models.

Findings

Stable NEC violation with quantum stability.

Perturbations propagate subluminally around the background.

The theory admits a Lorentz-invariant vacuum with a consistent S-matrix.

Abstract

We show that the DBI conformal galileons, derived from the world-volume theory of a 3-brane moving in an AdS bulk, admit a background, stable under quantum corrections, which violates the Null Energy Condition (NEC). The perturbations around this background are stable and propagate subluminally. Unlike other known examples of NEC violation, such as ghost condensation and conformal galileons, this theory also admits a stable, Poincare-invariant vacuum, with a Lorentz-invariant S-matrix satisfying standard analyticity conditions. Like conformal galileons, perturbations around deformations of the Poincare invariant vacuum propagate superluminally.