Dilatation symmetry in higher dimensions and the vanishing of the cosmological constant

TL;DR

This paper shows that in higher-dimensional theories with dilatation symmetry, the four-dimensional cosmological constant naturally vanishes without fine-tuning, and explores implications for dark energy and cosmological solutions.

Contribution

It demonstrates that dilatation symmetry in higher dimensions can lead to a zero cosmological constant and discusses the role of solutions and anomalies in cosmological evolution.

Findings

Vanishing cosmological constant without tuning

Existence of flat four-dimensional solutions with gauge couplings

Dilatation anomalies can generate observable dark energy

Abstract

A wide class of dilatation symmetric effective actions in higher dimensions leads to a vanishing four-dimensional cosmological constant. This requires no tuning of parameters and results from the absence of an allowed potential for the scalar dilaton field. The field equations admit many solutions with flat four-dimensional space and non-vanishing gauge couplings. In a more general setting, these are candidates for asymptotic states of cosmological runaway solutions, where dilatation symmetry is realized dynamically if a fixed point is approached as time goes to infinity. Dilatation anomalies during the runaway can lift the degeneracy of solutions and lead to an observable dynamical dark energy.