Gravitational waves from low-energy inflation by particle production

Gravitational waves from low-energy inflation by particle production
Ryo Namba, McGill University
Ryo Namba
Date and time: Tue, Apr 24, 2018 - 2:30pm
Location: LGRT419B
Category: ACFI Seminar
Abstract:

Detection of tensor mode fluctuations at the largest cosmological scales is often expected to provide a robust evidence of inflation and to fix the inflationary energy scale. Such direct connection is however applicable only when the tensor perturbations are effectively decoupled from other energy contents. In this talk I present a case exceptional to this starndard lore. When an SU(2) gauge field is prevented from diluting away by a coupling to a pseudo-scalar field, its perturbation can be amplified exponentially through the same coupling. This produced energy is then transferred to the metric tensor modes already at the linear level. While the SU(2) field is energetically subdominant to the inflaton, it can source gravitational waves to the amount considerably larger than the standard amplitude. I will discuss several potential constraints on the mechanism and demonstrate that detectable tensor-mode signals even for low-energy inflation.