Blue-tilted Primordial Gravitational Waves from Massive Gravity

Understand

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.