Holographic light dilaton at the conformal edge

TL;DR

This paper presents a holographic model demonstrating that the dilaton can be parametrically lighter than other composite states near the conformal edge, with its mass influenced by the anomalous dimension of the quark bilinear.

Contribution

It introduces a simple holographic framework showing the dilaton's lightness and its relation to conformality and anomalous dimensions, advancing understanding of scale symmetry breaking.

Findings

Dilaton can be parametrically lighter than other states near the conformal edge.

Dilaton mass depends on the anomalous dimension of the quark bilinear.

Dilaton saturates the anomalous Ward identity at low energy.

Abstract

We study a simple holographic model for gauge theories near the conformal edge to show that the dilaton can be parametrically lighter than any other composite states. The masses of all composite states, except the Nambu-Goldstone bosons like dilaton, are bounded by the infrared scale or the dynamical mass. The parametric dependence of the dilaton mass is controlled by the closeness of the anomalous dimension of the quark bilinear, that breaks spontaneously the scale symmetry, to the conformality. We also show in the holographic dual that under certain assumptions, the dilaton saturates at low energy the anomalous Ward identity for the dilatation currents.