# An Etude on Global Vacuum Energy Sequester

## TL;DR

This paper analyzes various approaches to vacuum energy sequester, highlighting how certain proposals require fine-tuning and comparing them to the original mechanism that avoids such issues in addressing the cosmological constant problem.

## Contribution

It clarifies the relationships between different non-local and global formulations of vacuum energy sequester and emphasizes the advantages of the original dynamical approach.

## Key findings

- Proposals without treating the cosmological constant as a dynamical variable require fine-tuning.
- Counterterms in some approaches need retuning at each loop order, similar to standard GR.
- Original vacuum energy sequester avoids fine-tuning problems present in other proposals.

## Abstract

Recently two of the authors proposed a mechanism of vacuum energy sequester as a means of protecting the observable cosmological constant from quantum radiative corrections. The original proposal was based on using global Lagrange multipliers, but later a local formulation was provided. Subsequently other interesting claims of a different non-local approach to the cosmological constant problem were made, based again on global Lagrange multipliers. We examine some of these proposals and find their mutual relationship. We explain that the proposals which do not treat the cosmological constant counterterm as a dynamical variable require fine tunings to have acceptable solutions. Furthermore, the counterterm often needs to be retuned at every order in the loop expansion to cancel the radiative corrections to the cosmological constant, just like in standard GR. These observations are an important reminder of just how the proposal of vacuum energy sequester avoids such problems.