Light dilaton from top-down holographic confinement with magnetic fluxes

TL;DR

This paper explores a class of strongly coupled, confining field theories with magnetic fluxes using holographic duals, revealing a light dilaton and analyzing stability and phase transitions in the model.

Contribution

It introduces a new two-parameter family of holographic models with magnetic fluxes, identifying a light dilaton and analyzing their stability and phase structure.

Findings

Identifies a light dilaton with mass much smaller than the confinement scale.

Finds no local instabilities in the fluctuation spectrum.

Discovers lines of first-order phase transitions in parameter space.

Abstract

A two-parameter class of higher-dimensional, strongly coupled, confining field theories in the presence of magnetic fluxes for two Abelian gauge groups admits a top-down, holographic dual description. The corresponding two-parameter family of regular background solutions of the classical equations of maximal supergravity in seven dimensions descends from maximal supergravity in eleven dimensions. We study the global and local stability properties of these solutions. We identify lines of zero-temperature first-order phase transitions, describing a polygon (a square) in the space of parameters, identified with the two fluxes. In the spectrum of fluctuations of the supergravity equations, interpreted as bound states of the dual, confining field theories, we find no evidence of local instabilities (tachyons). Over a significant portion of parameter space, that extends far away from the proximity to the transition, we identify an approximate dilaton, the mass of which is one order of magnitude smaller than the scale set by confinement. Our findings complement those emerging in other holographic models discussed in the literature, in which either the dilaton mass is only mildly lower than the confinement scale (when approaching a first-order transitions), or parametrically suppressed (when reaching the proximity to a second-order one).