Vacuum energy sequestering and cosmic dynamics

TL;DR

This paper investigates how a recent reformulation of general relativity that sequesters vacuum energy affects the evolution of homogeneous, isotropic universes with different matter contents, revealing significant differences except for radiation-like fluids.

Contribution

It explicitly analyzes the cosmological dynamics under vacuum energy sequestering, highlighting cases where the mechanism alters or preserves standard universe evolution.

Findings

Vacuum energy sequestering significantly impacts universe dynamics for most equations of state.

For radiation-like fluids ($w=1/3$), results match standard general relativity with zero cosmological constant.

Some well-behaved models in standard GR lack counterparts in the sequestering framework.

Abstract

We explicitly compute the dynamics of closed homogeneous and isotropic universes permeated by a single perfect fluid with a constant equation of state parameter $w$ in the context of a recent reformulation of general relativity, proposed in [1], which prevents the vacuum energy from acting as a gravitational source. This is done using an iterative algorithm, taking as an initial guess the background cosmological evolution obtained using standard general relativity in the absence of a cosmological constant. We show that, in general, the impact of the vacuum energy sequestering mechanism on the dynamics of the universe is significant, except for the $w=1/3$ case where the results are identical to those obtained in the context of general relativity with a null cosmological constant. We also show that there are well behaved models in general relativity that do not have a well behaved counterpart in the vacuum energy sequestering paradigm studied in this paper, highlighting the specific case of a quintessence scalar field with a linear potential.