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arXiv · 2105.12554

Beating the Lyth bound by parametric resonance during inflation

Yi-Fu Cai·Jie Jiang·Misao Sasaki·Valeri Vardanyan·Zihan Zhou
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Abstract

We propose a novel mechanism for enhancing the primordial gravitational waves without significantly affecting the curvature perturbations produced during inflation. This is achieved due to non-linear sourcing of resonantly amplified scalar field fluctuations. Our result is an explicit scale-dependent counter-example of the famous Lyth bound, which opens up a promising perspective of producing detectable inflationary tensor modes with low-scale inflation and a sub-Planckian field excursion. We explicitly demonstrate the testability of our mechanism with upcoming Cosmic Microwave Background B-mode observations.

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Yi-Fu Cai, Jie Jiang, Misao Sasaki, Valeri Vardanyan, Zihan Zhou. 2021-11-25. Beating the Lyth bound by parametric resonance during inflation. https://doi.org/10.1103/physrevlett.127.251301

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