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 f...[ Read more ]

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.