Cosmon inflation

TL;DR

This paper explores how the cosmon field, associated with dark energy, can also drive early universe inflation, producing realistic density fluctuations and specific predictions for spectral index and tensor-to-scalar ratio.

Contribution

It introduces a model where the cosmon field induces inflation with a nearly static geometry in the Jordan frame, linking dark energy dynamics to early universe inflation.

Findings

Predicts a spectral index n=0.97

Predicts tensor-to-scalar ratio r=0.13

Produces realistic primordial density fluctuations

Abstract

The cosmon field responsible for dynamical dark energy can induce an inflationary period in early cosmology. Details depend on dilatation symmetry breaking terms in its potential and kinetic term that are relevant only during early stages of the evolution of the universe. For a large range of parameters we find realistic primordial density fluctuations. As a particular example we discuss a model with almost static geometry in the Jordan frame for all epochs of cosmology. Here the cosmic evolution of the Hubble parameter is replaced by a variation of the Planck mass and particle masses. This model predicts a spectral index $n=0.97$ and a ratio for tensor to scalar fluctuations $r=0.13$.