Classical Cosmological Collider Physics and Primordial Features
  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.
