Cosmological Collider Physics

TL;DR

This paper explores how new particles during inflation leave distinctive signatures in primordial non-Gaussianities, revealing their masses, spins, and quantum nature through specific oscillatory and angular features in correlation functions.

Contribution

It provides a general, symmetry-based framework for understanding the signatures of particles with masses near the Hubble scale in cosmological fluctuations, extending previous scenario-specific analyses.

Findings

Distinctive power-law and oscillatory signatures in non-Gaussianities.

Angular dependence reveals particle spin information.

Quantum interference effects influence the phase of signals.

Abstract

We study the imprint of new particles on the primordial cosmological fluctuations. New particles with masses comparable to the Hubble scale produce a distinctive signature on the non-gaussianities. This feature arises in the squeezed limit of the correlation functions of primordial fluctuations. It consists of particular power law, or oscillatory, behavior that contains information about the masses of new particles. There is an angular dependence that gives information about the spin. We also have a relative phase that crucially depends on the quantum mechanical nature of the fluctuations and can be viewed as arising from the interference between two processes. While some of these features were noted before in the context of specific inflationary scenarios, here we give a general description emphasizing the role of symmetries in determining the final result.