Blue-tilted Primordial Gravitational Waves from Massive Gravity

TL;DR

This paper explores a massive gravity theory predicting blue-tilted primordial gravitational waves that are amplified and potentially detectable by interferometers, even if not observed on cosmic microwave background scales.

Contribution

It introduces a model where massive tensor gravitons produce detectable blue-tilted gravitational waves, distinct from standard massless graviton predictions.

Findings

Primordial gravitational waves can be significantly amplified in this massive gravity model.

The model predicts detectable signals for interferometers despite no CMB-scale detection.

Massive gravitons behave as non-relativistic matter after inflation, enhancing wave amplitudes.

Abstract

We study a theory of massive tensor gravitons which predicts blue-tilted and largely amplified primordial gravitational waves. After inflation, while their mass is significant until it diminishes to a small value, gravitons are diluted as non-relativistic matter and hence their amplitude can be substantially amplified compared to the massless gravitons which decay as radiation. We show that such gravitational waves can be detected by interferometer experiments, even if their signal is not observed on the CMB scales.