Probing Flavored Mesons of Confining Gauge Theories by Supergravity

TL;DR

This paper builds a gravity dual for a confining N=1 SU(N_c) gauge theory with massive fundamental flavors by embedding D7-brane probes in the Klebanov-Strassler background. The authors construct a smooth D7-brane configuration and analyze quadratic fluctuations to derive a 5d effective theory, from which they extract the vector and pseudo-scalar meson spectra. They find discrete spectra with a mass gap set by the glueball scale, with meson masses scaling as $M_{ ext{meson}}^2 \sim m^2$, where $m$ is the KS glueball scale, and show stability of the quadratic fluctuations. The results hinge on the probe approximation ($N_f \ll N_c$) and reveal a framework for studying flavored mesons in confining holographic models, while outlining future directions for fully backreacted flavors and closer connections to QCD phenomenology.

Abstract

We incorporate massive flavored fundamental quarks in the supergravity dual of N=1 SYM by introducing D7 brane probes to the Klebanov Strassler background. We find probe configurations that solve the D7 equations of motion. We compute the quadratic fluctuations of the D7 brane and extract the spectrum of vector and pseudo scalar flavored mesons. The spectra found are discrete and exhibit a mass gap of the order of the glueball mass.

Figures (2)

• Figure 1: Configuration of 7-branes on 2-sphere
• Figure 2: D7-probe configuration in a deformed conifold. The vectors denote the singular locus where the elliptic fibers get degenerate. The two shadowed surfaces that intersect with each vector are the 7-brane probes.