On Gauge Invariant Cosmological Perturbations in UV-modified Horava Gravity: A Brief Introduction

TL;DR

This paper analyzes gauge invariant cosmological perturbations in UV-modified Horava gravity, demonstrating the model's consistency with general relativity in IR and its potential to generate scale-invariant spectra without inflation.

Contribution

It shows that UV-modified Horava gravity can produce scale-invariant spectra in non-inflationary backgrounds, offering a new approach to early universe cosmology.

Findings

No extra graviton modes detected.

General relativity recovered in IR.

Scale-invariant spectra generated without inflation.

Abstract

We revisit gauge invariant cosmological perturbations in UV-modified, z = 3 Horava gravity with one scalar matter field, which has been proposed as a renormalizable gravity theory without the ghost problem in four dimensions. We confirm that there is no extra graviton modes and general relativity is recovered in IR, which achieves the consistency of the model. From the UV-modification terms which break the detailed balance condition in UV, we obtain scale-invariant power spectrums for non-inflationary backgrounds, like the power-law expansions, without knowing the details of early expansion history of Universe. This could provide a new framework for the Big Bang cosmology.