From inflation to dark energy through a dynamical Lambda: an attempt at alleviating fundamental cosmic puzzles

TL;DR

This paper proposes a cosmological model with a decaying vacuum energy density that smoothly connects inflation, radiation, dark matter, and dark energy phases, addressing key cosmic puzzles.

Contribution

It introduces a novel class of cosmologies with a dynamical Lambda that alleviates fundamental issues like the inflationary exit and the small current vacuum energy.

Findings

Spacetime emerges from a nonsingular de Sitter vacuum.

Smooth transition from inflation to radiation and dark energy.

Addresses the mismatch between inflationary and current vacuum energy.

Abstract

After decades of successful hot big-bang paradigm, Cosmology still lacks a framework in which the early inflationary phase of the universe smoothly matches the radiation epoch and evolves to the present `quasi' de Sitter spacetime. No less intriguing is that the current value of the effective vacuum energy density is vastly smaller than the value that triggered inflation. In this Essay we propose a new class of cosmologies capable of overcoming, or highly alleviating, some of these acute cosmic puzzles. Powered by a decaying vacuum energy density, the spacetime emerges from a pure nonsingular de Sitter vacuum stage, "gracefully" exits from inflation to a radiation phase followed by dark matter and vacuum regimes, and, finally, evolves to a late time de Sitter phase.