Dual String Theory Research Articles

Intersecting branes and adding flavors to the Maldacena-Nunez background

We study adding flavors into the Maldacena-N\u{u}nez background. It is achieved by introducing spacetime filling D9-branes or intersecting D5$'$-branes into the background with a wrapping D5-brane. Both D9-branes and D5$'$-branes can be spacetime filling from the 5D bulk point of view. At the probe limit it corresponds to introducing non-chiral fundamental flavors into the dual N=1 SYM. We propose a method to twist the fundamental flavor which has to involve open string charge. It reflects the fact that coupling fundamental matter to SYM in the dual string theory corresponds to adding an open string sector

Instability and degeneracy in the BMN correspondence

Non-degenerate perturbation theory, which was used to calculate the scale dimension of operators on the gauge theory side of the correspondence, breaks down when effects of triple trace operators are included. We interpret this as an instability of excited single-string states in the dual string theory for decay into the continuum of degenerate 3-string states. We apply time-dependent perturbation theory to calculate the decay widths from gauge theory. These widths are new gauge theory data which can be compared with future calculations in light cone string field theory.

Meson spectroscopy in AdS/CFT with flavour

We compute the meson spectrum of an N=2 super Yang-Mills theory with fundamental matter from its dual string theory on AdS_5 x S_5 with a D7-brane probe. For scalar and vector mesons with arbitrary R-charge the spectrum is computed in closed form by solving the equations for D7-brane fluctuations; for matter with non-zero mass m_q it is discrete, exhibits a mass gap of order m_q / sqrt(g_s N) and furnishes representations of SO(5) even though the manifest global symmetry of the theory is only SO(4). The spectrum of mesons with large spin J is obtained from semiclassical, rotating open strings attached to the D7-brane. It displays Regge-like behaviour for J << sqrt(g_s N), whereas for J >> sqrt(g_s N) it corresponds to that of two non-relativistic quarks bound by a Coulomb potential. Meson interactions, baryons and `giant gauge bosons' are briefly discussed.

On the Exact Evaluation of the Membrane Instanton Superpotential in M-Theory onG2-Holonomy Manifold

Following the work of Lima et al on the exact evaluation of the nonperturbative contribution to the superpotential from open-membrane instanton in Heterotic M-Theory, we evaluate systematically the contribution to the superpotential of a membrane instanton obtained by wrapping of a single M2 brane, once, on an isolated supersymmetric 3-cycle in a G_2-holonomy manifold. We then try to relate the results obtained to those sketched out in Harvey and Moore. We also do a heat-kernel asymptotics analysis to see whether one gets similar UV-divergent terms for (one or both of) the bosonic and fermionic determinants indicative of (partial) cancelation among them. The answer is in the affirmative, as expected by the supersymmetry of the starting membrane action. This work is a first step, both, in extending the work of Harvey and Moore to the evaluation of nonperturbative superpotentials for non-rigid supersymmetric 3-cycle wrappings, and in understanding the large N Chern-Simons/closed type-A topological string theory duality of Gopakumar and Vafa from M theory point of view.

Supersymmetric Defect Expansion in CFT from AdS Supertubes

The AdS/dCFT correspondence is used to show that a planar q-dimensional superconformal CFT defect expands, under the addition of electric charge and angular momentum, to a supersymmetric higher-dimensional defect of geometry R^q x C, where C is an arbitrary curve. The dual string theory process is the expansion of D-branes and fundamental strings into a supertube in an AdS background.

RG flows from Spin(7), CY 4-fold and HK manifolds to AdS, Penrose limits and pp waves

We obtain explicit realizations of holographic renormalization group (RG) flows from M-theory, from E^{2,1} \times Spin(7) at UV to AdS_4 \times \tilde{S^7} (squashed S^7) at IR, from E^{2,1} \times CY4 at UV to AdS_4 \times Q^{1,1,1} at IR, and from E^{2,1} \times HK (hyperKahler) at UV to AdS_4 \times N^{0,1,0} at IR. The dual type IIA string theory configurations correspond to D2-D6 brane systems where D6 branes wrap supersymmetric four-cycles. We also study the Penrose limits and obtain the pp-wave backgrounds for the above configurations. Besides, we study some examples of non-supersymmetric and supersymmetric flows in five-dimensional gauge theories.

Strings on Orbifolded PP-waves

We show that the string spectrum in the pp-wave limit of AdS_5\times S^5/Z_M (orbifolded pp-wave) is reproduced from the N=2 quiver gauge theory by quantizing the Green-Schwarz string theory on the orbifolded pp-wave in light cone gauge. We find that the twisted boundary condition on the world-sheet is naturally interpreted from the viewpoint of the quiver gauge theory. The correction of order g_{YM}^2 to the gauge theory operators agrees with the result in its dual string theory. We also discuss strings on some other orbifolded pp-waves.

Boundary States of D-Branes in AdS3 Based on Discrete Series

We study D-branes in the Lorentzian AdS_3 background from the viewpoint of boundary states, emphasizing the role of open-closed duality in string theory. Employing the world sheet with Lorentzian signature, we construct the Cardy states with the discrete series. We show that they are compatible with (1) unitarity and normalizability, and (2) the spectral flow symmetry, in the open string spectrum. We also discuss their brane interpretation. We further show that in the case of superstrings on AdS_3 x S^3 x T^4, our Cardy states yield an infinite number of physical BPS states in the open string channel, on which the spectral flows act consistently.

How Bob Laughlin tamed the giant graviton from Taub-NUT space

In this paper we show how two dimensional electron systems can be modeled by strings interacting with D-branes. The dualities of string theory allow several descriptions of the system. These include descriptions in terms of solitons in the near horizon D6-brane theory, non-commutative gauge theory on a D2-brane, the Matrix Theory of D0-branes and finally as a giant graviton in M-theory. The soliton can be described as a D2-brane with an incompressible fluid of D0-branes and charged string-ends moving on it. Including an NS5 brane in the system allows for the existence of an edge with the characteristic massless chiral edge states of the Quantum Hall system.

Non-supersymmetric SO(3)-invariant deformations of Script N = 1* vacua and their dual string theory description

We study the SO(3)-invariant relevant deformations of N=4 SU(N) gauge theory using the methods of Polchinski and Strassler. We present the region of parameter space where the non-supersymmetric vacuum is still described by stable ``dielectric'' five branes within the supergravity approximation.

String theory duals for mass-deformedSO(N)andUSp(2N)N=4supersymmetric Yang-Mills theories

We generalize the results of Polchinski and Strassler regarding the N=1-preserving mass deformation of N=4 SU(N) SYM theories and its string theory dual to SO(N) and USp(2N) gauge groups. The string theory duals involve 5-branes wrapped on RP^2. In order to match with the field theory classification of vacua, the 3-brane charge carried by such 5-branes must be shifted by a half, and this follows from a conjectured generalization of results of Freed and Witten. Our results provide an elegant physical picture for the classification of classically massive vacua in the mass-deformed N=4 theories.

Warping and vacua of (2+1)-dimensional super Yang-Mills theory

We use dielectric branes to find non singular string theory duals of a perturbed 2+1 dimensional gauge theory living on D2 branes. By adding fermion masses we obtain theories with reduced supersymmetry. The Higgs vacua of the perturbed theory correspond to polarization of the D2 branes into D4 branes. The confining vacua correspond to polarization of the D2 branes into NS5 branes. We consider different mass perturbations. Adding three equal masses preserves N=2 supersymmetry. In this case there are no confining vacua. By adding a fourth fermion mass we break all the supersymmetry, and find confining vacua. We also obtain duals for domain walls, condensates, baryon vertices, glueballs and flux tubes. We comment on the Kahler potentials for the Higgs and confining phases. In the course of the calculations we also find a nontrivial consistency check of the NS5 brane action in a D2 brane background.

A supergravity view of string dualities

We give an overview of the way in which the dualities of string theory are realized explicitly in a supergravity context. An illustrative example is the relation between the 8-brane of massive Romans type II string theory and M-theory.

Schwinger-Dyson = Wheeler-DeWitt: gauge theory observables as bulk operators

We argue that the second-order gauge-invariant Schwinger-Dyson operator of a gauge theory is the Wheeler-DeWitt operator in the dual string theory. Using this identification, we construct a set of operators in the gauge theory that correspond to excitations of gravity in the bulk. We show that these gauge theory operators have the expected properties for describing the semi-classical local gravity theory.

New N=1 superconformal field theories and their supergravity description

In this note we construct a new class of superconformal field theories as mass deformed N=4 super Yang–Mills theories. We will argue that these theories correspond to the fixed points which were recently found [1] studying the deformations of the dual IIB string theory on AdS 5× S 5.

Toric Geometry and Dualities of String Theory

It seems that all string theories and D = 11 supergravity are different limits of one underlying theory. These ‘different’ string theories are related by dualities. One of these leads to the following identifcations: Het[K3 × T2, VY] = IIB[Y] Het[ZX, VX] = F[X] Here Y and Z are Calabi–Yau threefolds, X is a Calabi–Yau fourfold and the V's on the right hand side remind us that heterotic compactifications depend, in general, on a background gauge field and hence on a vector bundle. The above identifications provide insight into the important class of (0,2) vacua in addition to providing a highly nontrivial test of string duality. The class of (0,2) vacua, although important is much less well understood than the more familiar class of (2,2) vacua. The (0,2) vacua require an understanding of vector bundles on Calabi–Yau manifolds and these are much less well understood than the Calabi–Yau manifolds themselves. The point of view adopted here is that the methods of Toric Geometry afford a certain systematization — many Calabi–Yau manifolds may be understood in terms of re exive polyhedra. The dualities above relate vector bundles on K3 surfaces to Calabi–Yau threefolds and vector bundles on Calabi–Yau threefolds to Calabi–Yau fourfolds. The right hand side of these identities can, in many cases, be related to re exive polyhedra so we would expect the left hand side to have also a natural interpretation in these terms. The subject of this telegraphic review is that this is in fact the case.

The large N limit of Script N = 2,1 field theories from threebranes in F-theory

We consider field theories arising from a large number of D3-branes near singularities in F-theory. We study the theories at various conformal points, and compute, using their conjectured string theory duals, their large $N$ spectrum of chiral primary operators. This includes, as expected, operators of fractional conformal dimensions for the theory at Argyres-Douglas points. Additional operators, which are charged under the (sometimes exceptional) global symmetries of these theories, come from the 7-branes. In the case of a $D_4$ singularity we compare our results with field theory and find agreement for large $N$. Finally, we consider deformations away from the conformal points, which involve finding new supergravity solutions for the geometry produced by the 3-branes in the 7-brane background. We also discuss 3-branes in a general background.

Solitons, black holes and duality in string theory

These lectures are intended as an introduction to some of the basic aspects of string solitons, duality and black holes. We begin with a discussion of the role of classical solutions in duality, then focus on string/string duality and fundamental membranes. Finally, we examine the feature of compositeness of string solitons, and its implications for bound states and black hole thermodynamics. As these lectures are aimed primarily at those less familiar with this field, technical details are minimized.

Duality in string theory

In these lectures we review some of the recent developments in string theory on an introductory and qualitative level. In particular we focus on S — T — U dualities of toroidally compactified ten-dimensional string theories and outline the connection to M-theory. Dualities among string vacua with less supersymmetries in six space-time dimensions is discussed and the concept of F-theory is briefly presented.

Transformation of black-hole hair under duality and supersymmetry

We study the transformation under the full string theory duality group of the observable charges (including mass, angular momentum, NUT charge, electric, magnetic and different scalar charges) of four-dimensional point-like objects whose asymptotic behavior constitutes a subclass closed under duality. We find that those charges fall into two complex four-dimensional representations of the duality group. T- duality (including Buscher's transformations) has an O(1, 2) action on them and S- duality a U(1) action. The generalized Bogomol'nyi bound is an U(2, 2)- invariant built out of one representation while the other representation (which includes the angular momentum) never appears in it. The bound is manifestly duality-invariant. Consistency between T- duality and supersymmetry seems to require that primary scalar hair is included in the generalized Bogomol'nyi bound. We also find that all known four-dimensional supersymmetric massless black holes are the T- duals in the time direction of the usual massive supersymmetric black holes. Non-extreme massless “black holes” can be found as the T- duals of the non-extreme black holes. All of them have primary scalar hair and naked singularities.