Symmetry Breaking and Axionic Strings in the Warped Deformed Conifold

TL;DR

This paper explores the interpretation of D-strings as axionic strings within the warped deformed conifold, revealing a massless pseudo-scalar glueball as a Goldstone boson and supporting the baryonic branch hypothesis in the dual gauge theory.

Contribution

It identifies the supergravity fluctuation spectrum with axionic strings and demonstrates the existence of a massless pseudo-scalar glueball as a Goldstone boson in the dual gauge theory.

Findings

Discovery of a massless pseudo-scalar glueball as a Goldstone boson.

Identification of a massless scalar glueball as a superpartner.

Support for the baryonic branch in the cascading gauge theory.

Abstract

We interpret D-strings at the bottom of the warped deformed conifold as axionic strings in the dual cascading SU(N+M) x SU(N) gauge theory. The axion is a massless pseudo-scalar glueball which we find in the supergravity fluctuation spectrum and interpret as the Goldstone boson of spontaneously broken U(1) baryon number symmetry. The existence of this massless glueball, anticipated in hep-th/0101013, supports the idea that the cascading gauge theory is on the baryonic branch, i.e. the U(1)_B global symmetry is broken by expectation values of baryonic operators. We also find a massless scalar glueball, which is a superpartner of the pseudo-scalar. This scalar mode is a mixture of an NS-NS 2-form and a metric perturbation of the warped deformed conifold of a type first considered in hep-th/0012034.