To boost or not to boost, that's the question

TL;DR

This paper explores the relationship between scale invariance and conformal invariance in cosmological correlators, highlighting how modified gravity theories like Einstein-Aether can break boost symmetry despite scale invariance.

Contribution

It provides a detailed analysis of how certain modified gravity theories exhibit scale invariance without conformal invariance, challenging assumptions in holographic dualities.

Findings

Einstein-Aether theory exemplifies scale invariance without boost symmetry.

Modified gravity theories can break conformal invariance in cosmological models.

Implications for dS/CFT and dS/SFT correspondences in non-unitary theories.

Abstract

Or should we talk about dS/CFT correspondence or dS/SFT correspondence in cosmological correlators? In non-unitary field theories -- which are conjectured to be dual to cosmological correlators -- scale invariance does not necessarily imply full conformal invariance. While general relativity predicts the emergence of conformal invariance (or boost symmetry in the bulk), various modified theories of gravity suggest only scale invariance, characterized by the absence of bulk boost symmetry. We demonstrate this distinction using Einstein-Aether theory as a canonical example.