Holographic Glueballs and Infrared Wall Driven by Dilaton

TL;DR

This paper investigates glueball spectra in holographic gauge theories with non-trivial dilaton backgrounds, revealing the necessity of an infrared wall for glueball existence and analyzing their spectra and Regge trajectories.

Contribution

It demonstrates the role of a dilaton-driven infrared wall in generating glueball spectra in holographic models, extending understanding of non-supersymmetric confining theories.

Findings

Glueball spectra appear only with an infrared wall in non-supersymmetric cases.

Glueball Regge slope is half that of flavor mesons.

Discrete spectra for low spin glueballs are obtained.

Abstract

We study glueballs in the holographic gauge theories, supersymmetric and non-super symmetric cases, which are given by the type IIB superstring solutions with non-trivial dilaton. In both cases, the dilaton reflects the condensate of the gauge field strength, $<F^2>$, which is responsible to the linear confining potential between the quark and anti-quark. Then we could see the meson spectra. On the other hand, the glueball spectra are not found in the supersymmetric case. We need a sharp wall, which corresponds to an infrared cutoff, in order to obtain the glueballs. In the non-supersymmetric case, the quantized glueballs are actually observed due to the existence of such a wall driven by the dilaton. The strings and D-branes introduced as building blocks of hadrons are pushed out by this wall, and we could see the Regge behavior of the higher spin meson and glueball states. We find that the slope of the glueball trajectory is half of the flavor meson's one. As for the low spin glueballs, they are studied by solving the fluctuations of the bulk fields, and their discrete spectra are shown.