Models of the Primordial Standard Clock

TL;DR

This paper develops a comprehensive inflationary model incorporating primordial Standard Clocks, which produce distinctive features in density perturbations, and compares its predictions with Planck 2013 CMB data to explore evidence for inflation or alternatives.

Contribution

It presents a full inflationary model of primordial Standard Clocks that realizes key theoretical features and assesses its compatibility with observational data.

Findings

Identified a marginal candidate signal in Planck 2013 data.

Demonstrated how future observations could test Standard Clock signals.

Provided a framework for distinguishing inflation from alternative scenarios.

Abstract

Oscillating massive fields in the primordial universe can be used as Standard Clocks. The ticks of these oscillations induce features in the density perturbations, which directly record the time evolution of the scale factor of the primordial universe, thus if detected, provide a direct evidence for the inflation scenario or the alternatives. In this paper, we construct a full inflationary model of primordial Standard Clock and study its predictions on the density perturbations. This model provides a full realization of several key features proposed previously. We compare the theoretical predictions from inflation and alternative scenarios with the Planck 2013 temperature data on Cosmic Microwave Background (CMB), and identify a statistically marginal but interesting candidate. We discuss how future CMB temperature and polarization data, non-Gaussianity analysis and Large Scale Structure data may be used to further test or constrain the Standard Clock signals.