Unique Fingerprints of Alternatives to Inflation in the Primordial Power Spectrum

TL;DR

This paper proposes a new mechanism where quantum fluctuations of massive fields act as standard clocks, producing scale-dependent oscillatory signals in the primordial power spectrum, which can distinguish different early universe scenarios.

Contribution

It introduces a novel mechanism for standard clocks in the primordial universe, applicable to alternative scenarios beyond inflation, via quantum fluctuations of massive fields.

Findings

Identifies scale-dependent oscillatory signals as signatures of massive fields.

Provides a model-independent way to distinguish early universe scenarios.

Suggests observational prospects for detecting these clock signals.

Abstract

Massive fields in the primordial universe function as standard clocks and imprint clock signals in the density perturbations that directly record the scale factor of the primordial universe as a function of time, a(t). A measurement of such signals would identify the specific scenario of the primordial universe in a model-independent fashion. In this Letter, we introduce a new mechanism through which quantum fluctuations of massive fields function as standard clocks. The clock signals appear as scale-dependent oscillatory signals in the power spectrum of alternative scenarios to inflation.