Phenomenology of the CAH+ measure

TL;DR

The paper explores the CAH+ measure's implications for multiverse cosmology, demonstrating its consistency with observations and absence of known measure pathologies.

Contribution

It provides a detailed phenomenological analysis of the CAH+ measure, showing it aligns with observed cosmological parameters and avoids common measure problems.

Findings

The distribution of the cosmological constant matches observations.

The measure predicts a realistic number of inflationary e-foldings.

It avoids runaway behaviors at zero or negative Lambda.

Abstract

The CAH+ measure regulates the infinite spacetime volume of the multiverse by constructing a surface of constant comoving apparent horizon (CAH) and then removing the future lightcones of all points on that surface (the latter prescription is referred to by the "+" in the name of the measure). This measure was motivated by the conjectured duality between the bulk of the multiverse and its future infinity and by the causality condition, requiring that the cutoff surfaces of the measure should be spacelike or null. Here we investigate the phenomenology of the CAH+ measure and find that it does not suffer from any known pathologies. The distribution for the cosmological constant Lambda derived from this measure is in a good agreement with the observed value, and the distribution for the number of inflationary e-foldings satisfies the observational constraint. The CAH+ measure does not exhibit any "runaway" behaviors at zero or negative values of Lambda, which have been recently shown to afflict a number of other measures.