# A Nonlocal Approach to the Cosmological Constant Problem

## TL;DR

This paper introduces a nonlocal gravitational model that cancels the cosmological constant by imposing a spacetime average constraint and utilizing a four-form gauge field, compatible with cosmological observations.

## Contribution

It presents a novel nonlocal approach combining a volume-form constraint and a four-form field to dynamically cancel the cosmological constant.

## Key findings

- Successfully cancels the cosmological constant from Einstein's equations
- Compatible with cosmic inflation and current acceleration
- Remains consistent with observational bounds on gravity modifications

## Abstract

We construct a model in which the cosmological constant is canceled from the gravitational equations of motion. Our model relies on two key ingredients: a nonlocal constraint on the action, which forces the spacetime average of the Lagrangian density to vanish, and a dynamical way for this condition to be satisfied classically with arbitrary matter content. We implement the former condition with a spatially-constant Lagrange multiplier associated with the volume form and the latter by including a free four-form gauge field strength in the action. These two features are enough to remove the cosmological constant from the Einstein equation. The model is consistent with all cosmological and experimental bounds on modification of gravity and allows for both cosmic inflation and the present epoch of acceleration.