In Search of Large Signals at the Cosmological Collider

TL;DR

This paper investigates the potential for detecting large oscillating signals in the primordial bispectrum caused by heavy particles during inflation, emphasizing the role of parity-odd chemical potentials for observability.

Contribution

It demonstrates that large signals require a parity-odd chemical potential, providing a new condition for observable signals in inflation models.

Findings

Current CMB data can detect signals in optimistic scenarios.

Future LSS and 21 cm surveys will expand detection prospects.

Large signals are unlikely without parity-odd chemical potential.

Abstract

We look for oscillating signals in the primordial bispectrum from new physics heavy particles which are visibly large for next generation large scale structures (LSS) survey. We show that in ordinary inflation scenarios where a slow-rolling inflaton generates density fluctuations and with no breaking of scale invariance or spacetime symmetry, there exist no naturally large signals unless the rolling inflaton generates a parity-odd chemical potential for the heavy particles. We estimate the accessibility of this signal through observations. While current CMB data are already sensitive in the most optimistic scenario, future probes, including LSS survey and 21 cm observation, can cover interesting regions of the model space.