Dynamical vacuum energy via adjustment mechanism

TL;DR

This paper proposes a novel adjustment mechanism involving a rapidly varying gravitational constant in the early universe to naturally reduce vacuum energy to observed levels, predicting a slow change and eventual contraction of the universe.

Contribution

It introduces a new model where vacuum energy is dynamically adjusted through early universe gravitational variations, addressing the cosmological constant problem.

Findings

Vacuum energy remains close to observed value at late times

Effective vacuum energy tends to a negative value, halting expansion

Model predicts eventual contraction of the universe

Abstract

A new mechanism of adjustment of vacuum energy down to the observed value from an initially huge one is considered. The mechanism is based on a very strong variation of the gravitational coupling constant in very early universe. The model predicts that the non--compensated remnant of vacuum energy changes very slowly at late stages of the cosmological evolution and is naturally close to the observed one. Asymptotically the effective vacuum energy tends to a negative value, so the cosmological expansion should stop and turn into contraction. There remains the problem of introduction of the usual matter into the model and therefore realising realistic cosmology.