Neutrino Signatures in Primordial Non-Gaussianities

TL;DR

This paper explores how neutrinos during inflation can produce distinctive oscillatory signals in the primordial bispectrum, with a focus on the effects of a chemical potential induced by the inflaton's slow-roll background, enhancing detectability.

Contribution

It introduces a detailed effective field theory analysis of neutrino signatures in primordial non-Gaussianities, including the impact of a chemical potential on oscillatory signals.

Findings

Neutrino mass spectrum influences bispectrum oscillations

Slow-roll inflation induces a chemical potential for neutrinos

Enhanced signals enable detection of heavy neutrinos without fine tuning

Abstract

We study the cosmological collider phenomenology of neutrinos in an effective field theory. The mass spectrum of neutrinos and their characteristic oscillatory signatures in the squeezed limit bispectrum are computed. Both dS-covariant and slow-roll corrections are considered, so is the scenario of electroweak symmetry breaking during inflation. Interestingly, we show that the slow-roll background of the inflaton provides a chemical potential for the neutrino production. The chemical potential greatly amplifies the oscillatory signal and makes the signal observably large for heavy neutrinos without the need of fine tuning.