Beyond Fab Four

TL;DR

This paper demonstrates that extended Fab Four theories, including additional Lagrangians beyond Horndeski, can be reformulated as simple generalizations of known terms, maintaining their self-tuning properties.

Contribution

It introduces a reformulation of beyond Horndeski theories as generalized Fab Four terms, preserving their key self-tuning features.

Findings

Extended Fab Four satisfy self-tuning properties

Additional Lagrangians can be expressed as generalizations of John and Paul

Maintains key properties of original Fab Four theories

Abstract

We show that the two additional Lagrangians that appear in theories beyond Horndeski can be reexpressed in terms of simple generalizations of the "John" and "Paul" terms of the Fab Four theories. We find that these extended Fab Four satisfy the same properties of self-tuning as the original Fab Four.