Large-Field Inflation and the Cosmological Collider

TL;DR

Large-field inflation models cause distinctive scale-dependent signals in the primordial bispectrum via spectator fields, offering a potential observational signature of large inflaton excursions linked to fundamental theories.

Contribution

This paper demonstrates how large-field inflation induces specific scale-dependent features in the bispectrum, connecting inflationary dynamics with the cosmological collider framework.

Findings

Scale dependence in spectator fields affects bispectrum shape.

Explicit example with tower states from the swampland conjecture.

Potential observational signatures of large-field inflation.

Abstract

Large-field inflation is a major class of inflation models featuring a near- or super-Planckian excursion of the inflaton field. We point out that the large excursion generically introduces significant scale dependence to spectator fields through inflaton couplings, which in turn induces characteristic distortions to the oscillatory shape dependence in the primordial bispectrum mediated by a spectator field. This so-called cosmological collider signal can thus be a useful indicator of large field excursions. We show an explicit example with signals from the "tower states" motivated by the swampland distance conjecture.