Standard Cosmology on the Anti-de Sitter boundary

TL;DR

This paper introduces a new Anti-de Sitter brane world cosmology model that aligns with the Lambda Cold Dark Matter model, avoids fine-tuning issues, and addresses key cosmological problems like the coincidence and cosmological constant problems.

Contribution

A novel AdS brane world model that eliminates quadratic energy density and reduces the cosmological constant problem using holographic renormalisation.

Findings

Model matches effective de Sitter Lambda CDM on the AdS boundary.

Near the boundary, the model agrees with Lambda CDM except at earliest times.

The model avoids the coincidence problem and mitigates the cosmological constant problem.

Abstract

The well-known brane world model of cosmology is an alternative to the standard model of cosmology, called {\Lambda}CDM (Lambda Cold Dark Matter) model. However, the quadratical energy density of the brane universe requires an undesirable fine tuning. The paper develops a new Anti-de Sitter (AdS) brane world model without the quadratical energy density by using a second Einstein equation, which arises canonically during a holographic renormalisation. On the AdS boundary it is demonstrated that this brane model equals an effective de Sitter {\Lambda}CDM model, whereas the brane model near the AdS boundary agrees to the {\Lambda}CDM model except the earliest times. Finally, it is shown that the coincidence problem is avoided and the cosmological constant problem, if not solved, is greatly reduced.