Theory HEP Seminar

Primordial Standard Clocks as a Direct Probe of the Scenario of the Primordial Universe

ingang Chen

Harvard CfA

How to observationally distinguish the inflation scenario from other possible alternative-to-inflation scenarios model-independently is an important challenge in modern astrophysics and cosmology. In particular, there has been criticism that the inflationary scenario is not experimentally falsifiable as a whole scenario. In this talk, we show that there are indeed observables, which are present generically in the primordial universe and potentially measurable, to address this challenge. These observables are induced by massive fields oscillating either classically or quantum-mechanically in the primordial epoch. Such oscillations can be regarded as primordial standard clocks. We show that the signals induced by these standard clocks in the primordial density perturbations directly record the defining property of the scenario of the primordial universe - the scale factor of the universe as a function of time, a(t).