Cosmological Constant and Axions in String Theory

TL;DR

This paper explores how string theory axions can serve as quintessence fields to explain the cosmological constant, analyzing conditions under which their potential energy matches observations.

Contribution

It identifies specific conditions in string compactifications that enable axion quintessence to account for the cosmological constant.

Findings

Large number of axions can produce the observed cosmological constant.

Axion potentials naturally align with observed dark energy scale.

Conditions on compactifications are crucial for axion quintessence viability.

Abstract

String theory axions appear to be promising candidates for explaining cosmological constant via quintessence. In this paper, we study conditions on the string compactifications under which axion quintessence can happen. For sufficiently large number of axions, cosmological constant can be accounted for as the potential energy of axions that have not yet relaxed to their minima. In compactifications that incorporate unified models of particle physics, the height of the axion potential can naturally fall close to the observed value of cosmological constant.