A natural cosmological constant from chameleons

TL;DR

This paper proposes a model where chameleon scalar fields naturally produce an effective cosmological constant, addressing the smallness and coincidence problems by linking the scalar field potential to matter density regions.

Contribution

It introduces a KKLT-inspired chameleon model that generates a cosmological constant-like effect through matter-dependent scalar field clustering.

Findings

Scalar field potential clusters around high-density regions.

The model explains the small, nonzero value of the cosmological constant.

Addresses the coincidence problem by linking $\

Abstract

We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru-Kallosh-Linde-Trivedi (KKLT)-inspired form of the potential and a particular chameleon coupling to the local density, patches of approximately constant scalar field potential cluster around regions of matter with density above a certain value, generating the effect of a cosmological constant on large scales. This construction addresses both the cosmological constant problem (why $\Lambda$ is so small, yet nonzero) and the coincidence problem (why $\Lambda$ is comparable to the matter density now).