Bulk Dynamics in Confining Gauge Theories

TL;DR

This paper develops a gauge-invariant approach to analyze bulk fluctuations in confining gauge theories via gauge/string duality, enabling the computation of glueball spectra and correlators.

Contribution

It introduces a covariant method for studying coupled scalar fluctuations in 5D supergravity models related to confining gauge theories.

Findings

Exact solutions for fluctuation equations in the UV approximation

Decoupling of scalar sectors in the UV for Klebanov-Strassler

Feasibility demonstrated for computing correlators in confining theories

Abstract

We consider gauge/string duality (in the supergravity approximation) for confining gauge theories. The system under scrutiny is a 5-dimensional consistent truncation of type IIB supergravity obtained using the Papadopoulos-Tseytlin ansatz with boundary momentum added. We develop a gauge-invariant and sigma-model-covariant approach to the dynamics of 5-dimensional bulk fluctuations. For the Maldacena-Nunez subsystem, we study glueball mass spectra. For the Klebanov-Strassler subsystem, we compute the linearized equations of motion for the 7-scalar system, and show that a 3-scalar sector containing the scalar dual to the gluino bilinear decouples in the UV. We solve the fluctuation equations exactly in the "moderate UV" approximation and check this approximation numerically. Our results demonstrate the feasibility of analyzing the generally coupled equations for scalar bulk fluctuations, and constitute a step on the way towards computing correlators in confining gauge theories.