Conjectures for Large N Superconformal N=4 Chiral Primary Four Point Functions

An expression for the four point function for half-BPS operators belonging to the [0,p,0] SU(4) representation in N=4 superconformal theories at strong coupling in the large N limit is suggested for any p. It is expressed in terms of the four point integrals defined by integration over AdS_5 and agrees with, and was motivated by, results for p=2,3,4 obtained via the AdS/CFT correspondence. Using crossing symmetry and unitarity, the detailed form is dictated by the requirement that at large N the contribution of long multiplets with twist less than 2p, which do not have anomalous dimensions, should cancel corresponding free field contributions.Comment: 50 pages, 1 figure, uses harvmac, version 2 extra reference, minor change

Quantum Strings and Bethe Equations

I briefly review the recently proposed construction of the Bethe ansatz which diagonalizes the Hamiltonian for quantum strings on AdS_5\times S^5 at large tension and restricted to the large charge states from a closed su(2) subsector.Comment: Latex, 6 pages, Talk delivered at RTN Workshop on the Quantum Structure of Space-time and the Geometric Nature of Fundamental Interactions and EXT Workshop on Fundamental Interactions and the Structure of Spacetime, Kolymbari, Crete, Greece, 5-10 Sep 200

Four-point correlators of BPS operators in N=4 SYM at order g^4

We study the large N degeneracy in the structure of the four-point amplitudes of 1/2-BPS operators of arbitrary weight k in perturbative N=4 SYM theory. At one loop (order g^2) this degeneracy manifests itself in a smaller number of independent conformal invariant functions describing the amplitude, compared to AdS_5 supergravity results. To study this phenomenon at the two-loop level (order g^4) we consider a particular N=2 hypermultiplet projection of the general N=4 amplitude. Using the formalism of N=2 harmonic superspace we then explicitly compute this four-point correlator at two loops and identify the corresponding conformal invariant functions. In the cases of 1/2-BPS operators of weight k=3 and k=4 the one-loop large N degeneracy is lifted by the two-loop corrections. However, for weight k > 4 the degeneracy is still there at the two-loop level. This behavior suggests that for a given weight k the degeneracy will be removed if perturbative corrections of sufficiently high order are taken into account. These results are in accord with the AdS/CFT duality conjecture.Comment: 45 pages, latex, 14 figure

Superconformal Ward Identities and their Solution

Superconformal Ward identities are derived for the the four point functions of chiral primary BPS operators for $\N=2,4$ superconformal symmetry in four dimensions. Manipulations of arbitrary tensorial fields are simplified by introducing a null vector so that the four point functions depend on two internal $R$-symmetry invariants as well as two conformal invariants. The solutions of these identities are interpreted in terms of the operator product expansion and are shown to accommodate long supermultiplets with free scale dimensions and also short and semi-short multiplets with protected dimensions. The decomposition into $R$-symmetry representations is achieved by an expansion in terms of two variable harmonic polynomials which can be expressed also in terms of Legendre polynomials. Crossing symmetry conditions on the four point functions are also discussed.Comment: 73 pages, plain Tex, uses harvmac, version 2, extra reference

Conformal Partial Wave Expansions for N=4 Chiral Four Point Functions

The conformal partial wave analysis of four point functions of half BPS operators belonging to the SU(4) [0,p,0] representation is undertaken for p=2,3,4. Using the results of N=4 superconformal Ward identities the contributions from protected short and semi-short multiplets are identified in terms of the free field theory. In the large N limit contributions corresponding to long multiplets with twist up to 2p-2 are absent. The anomalous dimensions for twist two singlet multiplets are found to order g^4 and agree with other perturbative calculations. Results for twist four and six are also found.Comment: 53 pages, uses harvmac, includes 1 figure, version 2 some corrections and minor extensions, version 3 some further corrections, version 4 as to be publishe

Superconformal Symmetry, Correlation Functions and the Operator Product Expansion

Superconformal transformations are derived for the $\N=2,4 supermultiplets corresponding to the simplest chiral primary operators. These are applied to two, three and four point correlation functions. When$\N=4$, results are obtained for the three point function of various descendant operators, including the energy momentum tensor and SU(4) current. For both$\N=2$ or 4 superconformal identities are derived for the functions of the two conformal invariants appearing in the four point function for the chiral primary operator. These are solved in terms of a single arbitrary function of the two conformal invariants and one or three single variable functions. The results are applied to the operator product expansion using the exact formula for the contribution of an operator in the operator product expansion in four dimensions to a scalar four point function. Explicit expressions representing exactly the contribution of both long and possible short supermultiplets to the chiral primary four point function are obtained. These are applied to give the leading perturbative and large N corrections to the scale dimensions of long supermultiplets.Comment: 75 pages, plain TeX file using harvmac; revised version, minor corrections and extra referenc

The Bound State S-Matrix for AdS5 x S5 Superstring

We determine the S-matrix that describes scattering of arbitrary bound states in the light-cone string theory in AdS5 x S5. The corresponding construction relies on the Yangian symmetry and the superspace formalism for the bound state representations. The basic analytic structure supporting the S-matrix entries turns out to be the hypergeometric function 4F3. We show that for particular bound state numbers it reproduces all the scattering matrices previously obtained in the literature. Our findings should be relevant for the TBA and Luescher approaches to the finite-size spectral problem. They also shed some light on the construction of the universal R-matrix for the centrally-extended psu(2|2) superalgebra.Comment: 37 pages, 2 figures, v2: typos correcte

On Exceptional Non-renormalization Properties Of N=4 SYM

We discuss non-renormalization properties of some composite operators in N=4 supersymmetric Yang-Mills theory.Comment: Contribution to the proceedings of the conference SUSY01 held in Dubna, June 2001; Latex, 4

Lifting asymptotic degeneracies with the Mirror TBA

We describe a qualitative feature of the AdS_5 x S^5 string spectrum which is not captured by the asymptotic Bethe ansatz. This is reflected by an enhanced discrete symmetry in the asymptotic limit, whereby extra energy degeneracy enters the spectrum. We discuss how finite size corrections should lift this degeneracy, through both perturbative (Luscher) and non-perturbative approaches (the Mirror TBA), and illustrate this explicitly on two such asymptotically degenerate states.Comment: v3, 20 pages, 1 figure, 2 tables, as publishe

Temperature quantization from the TBA equations

We analyze the Thermodynamic Bethe Ansatz equations for the mirror model which determine the ground state energy of the light-cone AdS_5 x S^5 superstring living on a cylinder. The light-cone momentum of string is equal to the circumference of the cylinder, and is identified with the inverse temperature of the mirror model. We show that the natural requirement of the analyticity of the Y-functions leads to the quantization of the temperature of the mirror model which has never been observed in any other models.Comment: 1+14 pages, v2: a paragraph added in section 2.