Gravitational Coupling and the Cosmological Constant

TL;DR

This paper proposes a dynamical mechanism where a large cosmological constant decays during universe expansion due to anomalous gravitational coupling of vacuum energy, with potential observational implications.

Contribution

It introduces a novel model where vacuum couples conformally to gravity, providing a mechanism for the decay of the cosmological constant during expansion.

Findings

The model allows a decaying cosmological constant during expansion.

It predicts observable consequences of the anomalous gravitational coupling.

The mechanism operates through conformal relation of two metric tensors.

Abstract

We deal with a dynamical mechanism in which a large cosmological constant, as suggested by inflationary scenarios, decays due to expansion of the universe. This mechanism has its origin in the gravitational coupling of the vacuum density. We assume that the vacuum couples anomalously to gravity that is the metric tensor that appears the gravitational part is not the same as that appears the matter part as suggested by weak equivalence principle. Instead, the two metric tensors are taken to be conformally related. We show that this provides a dynamical mechanism which works during expansion of the universe. We also consider some observational consequences of such a gravitational model.