121226107
Superstring vertex operators and scattering amplitudes on arbitrary Riemann surfaces
Abstract The construction of scattering amplitudes involving arbitrary bosonic mass level states is considered in both the closed superstring and in the heterotic string theories at any order of perturbation. From massless particle scattering on a general Riemann surface, the super-covariant form of the vertex operators is derived via factorization. The super-covariant rules, including the normal ordering prescription, to be used in computing amplitudes, are automatically given by this procedure.
119116593
Coulomb integrals and conformal blocks in the AdS3-WZNW model
We study spectral flow preserving four-point correlation functions in the AdS3-WZNW model using the Coulomb gas method on the sphere. We present a multiple integral realization of the conformal blocks and explicitly compute amplitudes involving operators with quantized values of the sum of their spins, i.e., requiring an integer number of screening charges of the first kind. The result is given as a sum over the independent configurations of screening contours yielding a monodromy invariant expansion in powers of the worldsheet moduli. We then examine the factorization limit and show that the leading terms in the sum can be identified, in the semiclassical limit, with products of spectral flow conserving three-point functions. These terms can be rewritten as the m-basis version of the integral expression obtained by J. Teschner from a postulate for the operator product expansion of normalizable states in the H3+-WZNW model. Finally, we determine the equivalence between the factorizations of a particular set of four-point functions into products of two three-point functions either preserving or violating spectral flow number conservation. Based on this analysis we argue that the expression for the amplitude as an integral over the spin of the intermediate operators holds beyond the semiclassical regime, thus corroborating that spectral flow conserving correlators in the AdS3-WZNW model are related by analytic continuation to correlation functions in the H3+-WZNW model.
122296725
Intrinsic normal-ordered vertex operators from the multiloop N-tachyon amplitude
Abstract We construct vertex operators for arbitrary mass level states of the closed bosonic string. Starting from a generalization of the Koba-Nielsen amplitude which is suitable for an arbitrary genus Riemann surface, we read the vertex operators from the residues of the poles for the intermediate states. Since the original expression is metric independent and normal ordered without the need of inventing any regularization scheme, our vertex operators also possess these properties. We discuss their general features.
1383405
Free field realization of superstring theory on AdS3
Fil: Hofman, Diego M. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina
117028101
Ten Years of AdS/CFT
125323277
String propagation in non-compact backgrounds
In this lecture we review some recent developments in non-rational conformal field theory, which allow a description of strings moving in non-compact backgrounds. In particular, we discuss recent progress in the SL(2,R) WZW model, which describes string propagation in AdS3.
119111243
Towards the string dual of tumbling and cascading gauge theories
Abstract We build type IIB backgrounds that can be interpreted as the dual description of field theories in which the dynamics shows many non-trivial phenomena, generalizing the baryonic branch of the Klebanov–Strassler system. We illustrate the steps of the explicit construction with a particularly interesting example. The dual field theory exhibits the expected behavior of an N = 1 supersymmetry gauge theory which, over different ranges of the radial direction, is undergoing a cascade of Seiberg dualities, a period of running, a cascade of Higgsings (tumbling) and finally gaugino condensation.
118674073
Unquenched Flavor in the Gauge/Gravity Correspondence
Within the AdS/CFT correspondence, we review the studies of field theories with a large number of adjoint and fundamental fields, in the Veneziano limit. We concentrate in set-ups where the fundamentals are introduced by a smeared set of D-branes. We make emphasis on the general ideas and then in subsequent chapters that can be read independently and describe particular considerations in various different models. Some new material is presented along the various sections.
119279945
WALKING DYNAMICS FROM STRING DUALS
Within the context of a string-theory dual to gauge theories with gauge group SU(Nc) and large Nc, we identify a class of solutions to the background equations for which a suitably defined dual of the gauge coupling exhibits the features of a walking theory. We find evidence for three distinct, dynamically generated scales, characterizing walking, symmetry breaking and confinement, and we put them in correspondence with field theory by an analysis of the operators driving the flow.
17880961
Fermions in bosonic string theories
We generalize the Jackiw-Rebbi-Hasenfratz-'t Hooft construction of fermions from bosons to demonstrate the fermionic nature of certain bound states involving SU(N) instantons in even spatial dimensions and SO(N) instantons in 8k+1 spatial dimensions. We use this result to identify several fermionic excitations in various perturbatively bosonic string theories. In some examples we are able to identify these fermions as excitations in known conformal field theories and independently confirm their fermionic nature. Examples of the fermions we find include certain 3-string junctions in type-0B theory, excitations of the 0-p system in type-0A theory, excitations of the stable D-particle of type-0 theory, and a rich spectrum of fermions in the bosonic string compactified on the SO(32) group lattice.
119258207
A tale of two cascades: Higgsing and Seiberg-duality cascades from type IIB string theory
A bstractWe construct explicitly new solutions of type IIB supergravity with brane sources, the duals of which are $ \mathcal{N} = {1} $ supersymmetric field theories exhibiting two very interesting phenomena. The far UV dynamics is controlled by a cascade of Seiberg dualities analog to the Klebanov-Strassler backgrounds. At intermediate scales a cascade of Higgsing appears, in the sense that the gauge group undergoes a sequence of spontaneous symmetry breaking steps which reduces its rank. Deep in the IR, the theory confines, and the gravity background has a non-singular end of space. We explain in detail how to generate such solutions, discuss some of the Physics associated with them and briefly comment on the possible applications.