Inflation driven by particle creation

TL;DR

This paper proposes a cosmological model where particle creation drives late-time acceleration and early inflation, alleviating cosmological constant problems and producing a scale-invariant primordial spectrum.

Contribution

It introduces a novel particle creation mechanism that explains both late-time acceleration and early inflation within a unified framework.

Findings

Vacuum energy density scales linearly with Hubble parameter

Model alleviates cosmological constant and coincidence problems

Predicts a scalar spectral index of 0.97 for inflation

Abstract

The creation of ultra-light dark particles in the late-time FLRW spacetime provides a cosmological model in accordance with precise observational tests. The matter creation backreaction implies in this context a vacuum energy density scaling linearly with the Hubble parameter H, which is consistent with the vacuum expectation value of the QCD condensate in a low-energy expanding spacetime. Both the cosmological constant and coincidence problems are alleviated in this scenario. We also explore the opposite, high energy limit of the particle creation process. We show that it leads to a non-singular primordial universe where an early inflationary era takes place, with natural reheating and exit. The generated primordial spectrum is scale invariant and, by supposing that inflation lasts for 60 e-folds, we obtain a scalar expectral index n = 0.97.