A Naturally Light Dilaton and a Small Cosmological Constant

TL;DR

This paper introduces a non-supersymmetric model with a naturally light dilaton, achieved through a 5D holographic approach involving a near-marginal operator, resulting in a small cosmological constant and a stable hierarchy.

Contribution

It provides a novel holographic model with a light dilaton and suppressed cosmological constant, including an exact scalar-gravity solution and a general dilaton potential.

Findings

Dilaton mass squared is suppressed by epsilon.

Cosmological constant is parametrically smaller than in SUSY models.

Provides a new holographic realization of broken conformal symmetry.

Abstract

We present a non-supersymmetric theory with a naturally light dilaton. It is based on a 5D holographic description of a conformal theory perturbed by a close-to-marginal operator of dimension 4-epsilon, which develops a condensate. As long as the dimension of the perturbing operator remains very close to marginal (even for large couplings) a stable minimum at hierarchically small scales is achieved, where the dilaton mass squared is suppressed by epsilon. At the same time the cosmological constant in this sector is also suppressed by epsilon, and thus parametrically smaller than in a broken SUSY theory. As a byproduct we also present an exact solution to the scalar-gravity system that can be interpreted as a new holographic realization of spontaneously broken conformal symmetry. Even though this metric deviates substantially from AdS space in the deep IR it still describes a non-linearly realized exactly conformal theory. We also display the effective potential for the dilaton for arbitrary holographic backgrounds.