We study oscillating string solutions in the Klebanov-Witten and its non-Abelian T-dual background dualised along an SU(2) isometry. We find the string energy as the function of oscillation number and angular momentum. We show that for a particular set of T-dual co-ordinates both the background have equal string states. We also study the string states where the strings are expanding and contracting in the T-dual co-ordinate direction. We expect the presence of the superconformal field theory dual operators whose anomalous dimensions depend on T-dual co-ordinate.
We calculate an unrefined limit of the superconformal index (the Schur-like index) of the Klebanov-Witten theory from the dual AdS side by using the recently developed giant graviton expansion method. Our formula includes multiple sums of the contribution of the D3-branes wrapped on three-cycles in the internal space. We numerically confirm the validity of our formula by comparing indices obtained by the formula with the gauge theory results.
In this paper we consider both Abelian as well as non-Abelian T-duals of the Klebanov-Witten background and inspect their various Penrose limits. We show that these backgrounds admit pp-wave solutions in the neighbourhood of appropriate null geodesics. We study the quantization of closed string propagating on some of the resulting pp-wave backgrounds and comment on the probable field theory duals.
We probe flavour branes in the Klebanov-Witten background in global coordinates. We show that supersymmetric probes correspond to massless flavours and analyse their spectrum of fluctuations. Our studies suggest that the mesons are dissociated by the Casimir energy. The spectrum is equidistant, with a ground state given by the conformal dimension of the operator dual to the fluctuations. We show that the equidistant structure of the spectrum arises from the addition of the angular momenta of the fundamental fields composing the meson operators.
We investigate 1/2 BPS conformal surface operators in the Klebanov-Witten theory. These surface operators preserve certain parts of the conformal symmetry and R-symmetry as well as half of the supersymmetry. We propose the gravity dual of the surface operator as a configuration of a D3-brane in AdS_5 x T^{1,1}. This D3-brane preserves the same amount of the supersymmetry as the surface operator. We also compute the correlation function of the surface operator and a chiral primary operator.
We study renormalization group flows among three dimensional superconformal gauge theories which closely resemble the renowned Klebanov-Witten flow in four dimensions. In the large N limit, each theory appearing in the flow is holographically dual to M-theory on AdS4 times a toric Sasaki-Einstein seven-manifold. The theories are obtained through the so-called flavoring method, which adds some fundamental matter fields to the dimensionally reduced Klebanov-Witten theories. We reconfirm the matching between the gauge theories and the dual geometries by comparing the chiral ring structure. As a m…
Using AdS/CFT, we study the addition of an arbitrary number of backreacting flavors to the Klebanov-Witten theory, making many checks of consistency between our new Type IIB plus branes solution and expectations from field theory. We study generalizations of our method for adding flavors to all N=1 SCFTs that can be realized on D3-branes at the tip of a Calabi-Yau cone. Also, general guidelines suitable for the addition of massive flavor branes are developed.
In this paper we find various new backgrounds in Type IIB, IIA and M-theory with an $AdS_3$-factor. The solutions are smooth and preserve small amounts of SUSY. These new backgrounds are found by application of non-Abelian T-duality (sometimes combined with T-duality) on the supergravity solution dual to the Klebanov-Witten CFT compactified to two dimensions. The field theory aspects encoded by these backgrounds are studied. We give a detailed account of conserved charges, central charges, entanglement entropy and Wilson loops. Further, we present a possible field theory interpretation for our…
In this paper we study an $AdS_5$ solution constructed using non-Abelian T-duality, acting on the Klebanov-Witten background. We show that this is dual to a linear quiver with two tails of gauge groups of increasing rank. The field theory dynamics arises from a D4-NS5-NS5' brane set-up, generalizing the constructions discussed by Bah and Bobev. These realize $\mathcal{N}=1$ quiver gauge theories built out of $\mathcal{N}=1$ and $\mathcal{N}=2$ vector multiplets flowing to interacting fixed points in the infrared. We compute the central charge using $a$-maximization, and show its precise agreem…
We study D-instanton solutions in type IIB supergravity on $AdS_5\times T^{1,1}$, which has a dual ${\cal N}=1$ $SU(N)\times SU(N)$ super Yang-Mills theory. Apart from ordinary D(-1)-brane instantons, we discuss wrapped D1-branes over minimal 2-cycles and derive explicit solutions preserving half the supersymmetries. These solutions are identified with Yang-Mills instantons which are (anti)self-dual in both gauge group factors with instanton charge $(k,k')$. By examining the boundary behaviour of the solutions we discuss the coupling to the corresponding dual boundary operators, and identify t…
We consider the addition of a large number of massive dynamical flavors to the Klebanov-Witten theory, the quiver gauge theory describing the low energy dynamics of Nc D3-branes at the conifold singularity. Massive flavors are introduced by means of Nf D7-branes which are holomorphically embedded and smeared along the transverse directions. After some general comments on the validity of the smearing procedure, we find the full backreacted supergravity solution corresponding to a particular class of massive embeddings. The solution depends on a running effective number of flavors, whose functio…
In this sequel to [L-Y1], [L-L-S-Y], and [L-Y2] (respectively arXiv:0709.1515 [math.AG], arXiv:0809.2121 [math.AG], and arXiv:0901.0342 [math.AG]), we study a D-brane probe on a conifold from the viewpoint of the Azumaya structure on D-branes and toric geometry. The details of how deformations and resolutions of the standard toric conifold $Y$ can be obtained via morphisms from Azumaya points are given. This should be compared with the quantum-field-theoretic/D-brany picture of deformations and resolutions of a conifold via a D-brane probe sitting at the conifold singularity in the work of Kle…
We consider three-parameter Yang-Baxter deformations of the $AdS_5\times T^{1,1}$ superstring for abelian $r$-matrices which are solutions of the classical Yang-Baxter equation. We find two new backgrounds which are dual to the dipole deformed Klebanov-Witten gauge theory and to the nonrelativistic Klebanov-Witten gauge theory with Schrödinger symmetry
We study semiclassical strings in the Klebanov-Witten and in the Non-abelian T-dual Klebanov-Witten backgrounds. We show that both backgrounds share a subsector of equivalent states up to conditions on the T-dual coordinates which also impose a breaking of the R-symmetry by a discrete group. We also analyze string configurations where the strings are stretched along the T-dual coordinates. This semiclassical analysis predicts the existence of chiral primary operators for the dual (strongly coupled) superconformal field theory whose anomalous dimension depends on the T-dual coordinates. We brie…
The Klebanov-Strassler background is invariant under the Z_2 symmetry I, which acts by exchanging the bi-fundamental fields A and B, accompanied by the charge conjugation. We study the background perturbations in the I-odd sector and find an exhaustive list of bosonic states invariant under the global SU(2)*SU(2) symmetry. In addition to the scalars identified in an earlier publication arXiv:0712.4404 we find 7 families of massive states of spin 1. Together with the spin 0 states they form 3 families of massive vector multiplets and 2 families of massive gravitino multiplets, containing a vect…
We examine the extension of the Klebanov-Witten gauge/gravity correspondence away from the low-energy conformal limit, to a duality involving the full, asymptotically Ricci-flat background describing three-branes on the conifold. After a discussion of the nature of this duality at the string theory level (prior to taking any limits), we concentrate on the intermediate-energy regime where excited string modes are negligible but the branes are still coupled to the bulk. Building upon previous work, we are able to characterize the effective D3-brane worldvolume action in this regime as an IR defo…
We expand on Klebanov and Witten's recent proposal for formulating the AdS/CFT correspondence using irregular boundary conditions. The proposal is shown to be correct to any order in perturbation theory.
We show that the entanglement of purification and the critical distance between the two mixed systems is a powerful measure in probing the phase structures of QCD and confining backgrounds, as it can distinguish the scale of chiral symmetry breaking versus the scale of confinement/deconfinement phase transitions. For two symmetric strips with equal and finite width and infinite length, and in the background of several confining geometries, we numerically calculate the critical distance between them where the mutual information vanishes and show that this quantity can probe the very rich phase …
Supersymmetric probe branes satisfy the kappa-symmetry condition which ensures that the action is minimized with respect to both variations of the embedding and of the world-volume gauge field. We observe that the kappa-symmetry condition for a D7-brane in an imaginary self-dual (ISD) background can be generalized yielding minimization of the action with respect to variations of the gauge field only but not of the embedding. This provides a new way to construct non-BPS solutions for D7-branes once the embedding extremizes the geometrical volume of the brane. We then apply this method to the Kl…
We present a new class of string theory solutions which are conjectured to be dual to the N=1 conifold theory by Klebanov and Witten coupled to non chiral massive dynamical flavors. These are introduced, in the Veneziano limit, by means of suitably embedded and smeared D7-branes whose full backreaction on the background is taken into account. The string solutions are used to study chromoelectric charge screening effects due to the dynamical flavors in the non perturbative regime of the dual gauge theories.
Using methods of Hamiltonian dynamical systems, we show analytically that a dynamical system connected to the classical spinning string solution holographically dual to the principal Regge trajectory is non-integrable. The Regge trajectories themselves form an integrable island in the total phase space of the dynamical system. Our argument applies to any gravity background dual to confining field theories and we verify it explicitly in various supergravity backgrounds: Klebanov-Strassler, Maldacena-Nunez, Witten QCD and the AdS soliton. Having established non-integrability for this general cla…
We propose a number of new Seiberg dualities of N=1 quiver gauge theories. The new Seiberg dualities originate in new S-dualities of N=2 superconformal field theories recently proposed by Gaiotto. N=2 S-dual theories deformed by suitable mass terms flow to our N=1 Seiberg dual theories. We show that the number of exactly marginal operators is universal for these Seiberg dual theories and the 't Hooft anomaly matching holds for these theories. These provide strong evidence for the new Seiberg dualities. Furthermore, we study in detail the Klebanov-Witten type theory and its dual as a concrete e…
We review various K-theory classification conjectures in string theory. Sen conjecture based proposals classify D-brane trajectories in backgrounds with no H flux, while Freed-Witten anomaly based proposals classify conserved RR charges and magnetic RR fluxes in topologically time-independent backgrounds. In exactly solvable CFTs a classification of well-defined boundary states implies that there are branes representing every twisted K-theory class. Some of these proposals fail to respect the self-duality of the RR fields in the democratic formulation of type II supergravity and none respect S…
We construct the non-relativistic counterparts of some well-known supergravity solutions dual to relevant and marginal deformations of N=4 super Yang-Mills. The main tool we use is the null Melvin twist and we apply it to the N=1 and N=2* Pilch-Warner RG flow solutions as well as the Lunin-Maldacena solution dual to beta-deformations of N=4 super Yang-Mills. We also obtain a family of supergravity solutions with Schrodinger symmetry interpolating between the non-relativistic version of the N=1 Pilch-Warner and Klebanov-Witten fixed points. A generic feature of these non-relativistic background…
In this thesis we study some applications of the gauge/gravity correspondence. In chapter 1 we introduce the gauge/gravity conjecture focusing on the aspects that will be relevant in the rest of the work, in chapter 2 we extend the Gubser-Klebanov-Polyakov-Witten (GKPW) prescription generalizing it to gravity backgrounds with two boundaries. In chapter 3 we discuss the Maldacena-Rey prescription to compute the quark-antiquark (and monopole-antimonopole) potential in some gravity backgrounds duals to conformal and non-conformal field theories. In particular, we analyze the stability of the clas…
We propose to study a generalization of the Klebanov-Polyakov-Witten (KPW) construction for the algebra of observables in the $c = 1$ string model to theories with $c > 1$. We emphasize the algebraic meaning of the KPW construction for $c = 1$ related to occurrence of a {\it model} of {\it SU}(2) as original structure on the algebra of observables. The attempts to preserve this structure in generalizations naturally leads to consideration of $W$-gravities. As a first step in the study of these generalized KPW constructions we design explicitly the subsector of the space of observables in appro…
The duality cascade, and its dual description as string theory on the warped deformed conifold, brings together several sophisticated topics, some of which are not widely known. These lectures, which contain a number of previously unpublished results, and are intended for experts as well as students, seek to explain the physics of duality cascades. Seiberg duality is carefully introduced, with detailed attention to the physical implications of duality away from the far infrared. The conifold is briefly introduced and strings on the conifold (the Klebanov-Witten model) are discussed. Next, frac…
We propose the dual gravity of a non conformal gauge theory which has logarithmic running of couplings in the IR but becomes almost conformal in the far UV. The theory has matter in fundamental representation, non-zero temperature and under a cascade of Seiberg dualities, can be described in terms of gauge groups of lower and lower rank. We outline the procedure of holographic renormalization and propose a mechanism to UV complete the gauge theory by modifying the dual geometry at large radial distances. As an example, we construct the brane configuration and sources required to attach a Kleba…
We explore the string spectrum in the Witten QCD model by considering classical string configurations, thereby obtaining energy formulas for quantum states with large excitation quantum numbers representing glueballs and Kaluza-Klein states. In units of the string tension, the energies of all states increase as the 't Hooft coupling $λ$ is decreased, except the energies of glueballs corresponding to strings lying on the horizon, which remain constant. We argue that some string solutions can be extrapolated to the small $λ$ regime. We also find the classical mechanics description of supergravit…
We speculate that the weak gravity conjecture applied to theories with holographic duals bans the existence of disordered phases at zero temperature. We test this idea by introducing a non-zero baryon chemical potential in a deformation of the $SU(N_c)\times SU(N_c)$ Klebanov-Witten gauge theory with broken supersymmetry and conformal invariance. At low temperature, a disordered phase dual to a black brane geometry is unstable for low chemical potentials and metastable for high values. In the metastable phase, states with a partial Higgsing of the gauge group are favored over the normal disord…
We study the low-energy effective action on confining strings (in the fundamental representation) in SU(N) gauge theories in D space-time dimensions. We write this action in terms of the physical transverse fluctuations of the string. We show that for any D, the four-derivative terms in the effective action must exactly match the ones in the Nambu-Goto action, generalizing a result of Luscher and Weisz for D=3. We then analyze the six-derivative terms, and we show that some of these terms are constrained. For D=3 this uniquely determines the effective action for closed strings to this order, w…
