Classical Cosmological Collider Physics and Primordial Features

TL;DR

This paper explores how classical features in inflation can excite heavy particles beyond the Hubble scale, producing observable non-Gaussian signatures that extend the reach of cosmological collider physics.

Contribution

It introduces mechanisms by which classical primordial features can excite heavy fields, enabling detection of particles with masses much larger than the Hubble scale.

Findings

Classical oscillations can excite heavy fields without Boltzmann suppression.

Sharp features in inflation can produce observable non-Gaussianities.

Heavy particle spectra can be inferred from primordial non-Gaussian signals.

Abstract

Features in the inflationary landscape can inject extra energies to inflation models and produce on-shell particles with masses much larger than the Hubble scale of inflation. This possibility extends the energy reach of the program of cosmological collider physics, in which signals associated with these particles are generically Boltzmann-suppressed. We study the mechanisms of this classical cosmological collider in two categories of primordial features. In the first category, the primordial feature is classical oscillation, which includes the case of coherent oscillation of a massive field and the case of oscillatory features in the inflationary potential. The second category includes any sharp feature in the inflation model. All these classical features can excite unsuppressed quantum modes of other heavy fields which leave observational signatures in primordial non-Gaussianities, including the information about the particle spectra of these heavy degrees of freedom.