Aspects of Gauge-Gravity Duality

Abstract

In this Ph.D. thesis, we study various backgrounds in Type IIB supergravity which admit interpretations in terms a dual field theory, and compute properties such as effective potentials and spectra, using both holographic and field theoretic methods. First, we study the phase structure of beta-deformed N=4 SYM on S3 at weak and strong 't Hooft coupling. We compute the one-loop effective potential, and find that at near critical chemical potential and small finite temperature, there is a metastable state at the origin of moduli space. We derive the gravitational background describing the theory at strong coupling, and by performing a probe-brane calculation, we find qualitative agreement between the weak and strong coupling results. Next, we study gravitational backgrounds obtained by wrapping Nc D5 color branes on an S2 inside a CY3-fold, and Nf D5 backreacting flavor branes on a non-compact two-cycle inside the same CY3-fold. These backgrounds are believed to be dual to certain SQCD-like theories. We compute how the spectrum depends on the number of flavors, and find that the mass of the lightest scalar glueball increases with the number of flavors until the point Nf=2Nc is reached after which the opposite behaviour is observed. Finally, we consider a class of backgrounds that exhibit walking behaviour, i.e. a suitably defined four-dimensional gauge coupling stays nearly constant in an intermediate energy regime. The breaking of approximate scale invariance has been conjectured to lead to the existence of a light scalar in the spectrum. This so-called dilaton would be the pseudo-Goldstone boson of dilatations. Using holographic techniques, we compute the spectrum and find a light state whose mass is suppressed by the length of the walking region, suggesting that this might be the dilaton.

Ph.D. Thesis. 119 pages. 13 figures

References in corpus (20)

• Chiral symmetry breaking as open string tachyon condensation
• Zero of the discrete beta function in SU(3) lattice gauge theory with color sextet fermions
• The physics of eight flavours
• Phase Diagram of N=4 Super-Yang-Mills Theory with R-Symmetry Chemical Potentials
• Phase structure of SU(3) gauge theory with two flavors of symmetric-representation fermions
• Glueballs vs. Gluinoballs: Fluctuation Spectra in Non-AdS/Non-CFT
• Klebanov-Witten theory with massive dynamical flavors
• Comments on the String dual to N=1 SQCD
• Blackhole/String Transition for the Small Schwarzschild Blackhole of $Ad{S}_5\times S^5$ and Critical Unitary Matrix Models
• Heavy quark potential with dynamical flavors: a first order transition
• Matching the Hagedorn temperature in AdS/CFT
• The supergravity dual of 3d supersymmetric gauge theories with unquenched flavors
• Screening effects on meson masses from holography
• Holographic flavor in N=4 gauge theories in 3d from wrapped branes
• A Note on the String Dual of N=1 SQCD-like Theories
• Phase transitions in large N(c) heavy quark potentials
• Hagedorn Systems from Backreacted Finite Temperature N_f=2N_c Backgrounds
• Unquenched flavors in the Klebanov-Strassler theory
• Extending BCCNR flavored geometry to the negative coupling constant region
• Phase Structure of Beta-deformed N=4 SYM on S^3 with Chemical Potentials