New cosmological colliders as detectors for particles in early universe

Abstract

Our universe is believed to start with an inflationary epoch. During inflation, spacetime is perturbed due to fluctuations generated by quantum effects, and can be measured from observations such as CMB. Cosmological collider is a theoretical method to extract information of early particles from correlation functions of primordial perturbations. This is a powerful tool to check or constrain new physics, cause the inflationary energy can be extremely high, and early particles can generally couple to inflatons and leave imprints. The initial consideration for cosmological colliders is the curvature perturbations contributed directly by inflaton fluctuations. However, the inflaton cosmological collider meets the challenge that its signal is often suppressed. So we turn to rich mechanisms for other early fluctuations, which record new particles and convert to primordial perturbations. In this thesis, we introduce our works on new cosmological colliders from some popular models.

Date of Award	2022
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Yi WANG (Supervisor)