More AdS_3 correlators

We compute three-point functions for the $SL(2,\mathbb R)$-WZNW model. After reviewing the case of the two-point correlator, we compute spectral flow preserving and nonpreserving correlation functions in the space-time picture involving three vertex operators carrying an arbitrary amount of spectral flow. When only one or two insertions have nontrivial spectral flow numbers, the method we employ allows us to find expressions without any constraint on the spin values. Unlike these cases, the same procedure restrains the possible spin configurations when three vertices belong to nonzero spectral flow sectors. We perform several consistency checks on our results. In particular, we verify that they are in complete agreement with previously computed correlators involving states carrying a single unit of spectral flow.Comment: 22 pages. Minor changes. Some references adde

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.Comment: 28 pages; references modified, published versio

Some recursive formulas for Selberg-type integrals

A set of recursive relations satisfied by Selberg-type integrals involving monomial symmetric polynomials are derived, generalizing previously known results. These formulas provide a well-defined algorithm for computing Selberg-Schur integrals whenever the Kostka numbers relating Schur functions and the corresponding monomial polynomials are explicitly known. We illustrate the usefulness of our results discussing some interesting examples.Comment: 11 pages. To appear in Jour. Phys.

Coulomb integrals for the SL(2,R) WZNW model

We review the Coulomb gas computation of three-point functions in the SL(2,R) WZNW model and obtain explicit expressions for generic states. These amplitudes have been computed in the past by this and other methods but the analytic continuation in the number of screening charges required by the Coulomb gas formalism had only been performed in particular cases. After showing that ghost contributions to the correlators can be generally expressed in terms of Schur polynomials we solve Aomoto integrals in the complex plane, a new set of multiple integrals of Dotsenko-Fateev type. We then make use of monodromy invariance to analytically continue the number of screening operators and prove that this procedure gives results in complete agreement with the amplitudes obtained from the bootstrap approach. We also compute a four-point function involving a spectral flow operator and we verify that it leads to the one unit spectral flow three-point function according to a prescription previously proposed in the literature. In addition, we present an alternative method to obtain spectral flow non-conserving n-point functions through well defined operators and we prove that it reproduces the exact correlators for n=3. Independence of the result on the insertion points of these operators suggests that it is possible to violate winding number conservation modifying the background charge.Comment: Improved presentation. New section on spectral flow violating correlators and computation of a four-point functio

KMS states and modular theory in topological *-algebras

En el presente trabajo analizamos qué estructuras propias de la teoría modular de Tomita y Takesaki en álgebras de von Neumann estándar pueden extenderse al caso de ⋆-álgebras topológicas más generales. Para ello demostramos, en primer lugar, que es posible establecer una biyección entre el espacio de formas lineales positivas continuas sobre una ⋆-álgebra con unidad localmente convexa A y el conjunto Cycl(A) de las clases de equivalencia unitaria de sus ⋆-representaciones cerradas débilmente continuas fuertemente c´ıclicas, generalizando así el clásico teorema de la construcción GNS que se plantea habitualmente en el marco de las C⋆-álgebras con unidad. Probamos asimismo que, en el caso en que el álgebra A es tonelada y cuasicompleta, esta biyección puede extenderse, siempre a menos de equivalencia unitaria, a una biyección entre el conjunto de los subespacios hilbertianos inmersos en el espacio anti- dual topológico d´ebil de A, A×, que son ⋆-estables frente a la acción antidual regular izquierda de A sobre A× y la colecci´on de los respectivos núcleos re- reproductivos. A continuación demostramos que esta biyección múltiple puede hacerse un isomorfismo c ́onico trasladando adecuadamente la estructura de cono regular estrictamente convexo que presenta el conjunto de subespacios hilbertianos al que nos referimos a los demás espacios involucrados en el teorema. Por último, discutimos las implicaciones de estos resultados en el contexto de los estados KMS y de la teoría modular de Tomita-Takesaki. En particular, demostramos que si β es cualquier n´umero real y A es una ⋆-álgebra con unidad localmente convexa tonelada cuasicompleta nuclear sobre la que act´ua un grupo continuo monoparamétrico de ⋆-automorfismos de crecimiento a lo sumo polinomial α, toda funcional (α, β)-KMS sobre A tiene una única descomposición integral en t´erminos de funcionales (α, β)-KMS extremales.In this thesis we analyse which structures from Tomita-Takesaki modular theory on von Neumann algebras can be extended when the topology on the algebra is more general. In order to do that, we prove that there is a bijection between the space of positive linear continuous forms on a locally con- vex ⋆-algebra A with unit and the set Cycl(A) of unitary equivalence classes of its closed weakly continuous strongly cyclic ⋆-representations, a bijection that generalizes the classical GNS construction theorem usually proved for the unital C⋆-algebra case. After that we prove that, when the algebra A is barrelled and quasi-complete, this bijection can be extended, up to unitary equivalence, to a bijection between the set of Hilbert subspaces embedded in the topological antidual space of A, A×, that are ⋆-invariant under the regular left antidual action of A on A×, and the collection of the corresponding po- sitive kernels relative to A×. It is also proved that this bijection can be made a cone isomorphism by translating the strict convex regular cone structure the Hilbert subspaces set has to the other spaces involved in the theorem. We discuss the implications of these results in the context of KMS states and Tomita-Takesaki modular theory. In particular, if β is any real number, A is a locally convex quasi-complete barrelled nuclear ⋆-algebra with unit and α is a continuous monoparametric group of ⋆-automorphisms of at most poli- nomial growth acting on A, every (α, β)-KMS functional on A has a unique integral decomposition in terms of extremal (α, β)-KMS functionals.Fil: Iguri, Sergio M.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina