The cosmon model for an asymptotically vanishing time-dependent cosmological ``constant''

TL;DR

This paper explores a gravity-scalar field model where the scalar's energy influences a time-dependent cosmological constant, potentially aligning with current cosmological observations and addressing naturalness issues.

Contribution

It introduces a cosmon model with a scalar field that dynamically adjusts the cosmological constant to match matter and radiation energy densities.

Findings

The cosmological constant vanishes asymptotically.

The model naturally explains the smallness of the current cosmological constant.

Potential implications for late-time cosmology are discussed.

Abstract

We investigate the coupled system of gravity and a scalar with exponential potential. The energy momentum tensor of the scalar field induces a time-dependent cosmological ``constant''. This adjusts itself dynamically to become in the ``late'' universe (including today) proportional to the energy density of matter and radiation. Possible consequences for the present cosmology are shortly discussed. We also address the question of naturalness of the cosmon model.