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ABSTRACT: We present a summary of current knowledge about the AGT relations for
conformal blocks with additional insertion of the simplest degenerate operator,
and a special choice of the corresponding intermediate dimension, when the
conformal blocks satisfy hypergeometric-type differential equations in position
of the degenerate operator. A special attention is devoted to representation of
conformal block through the beta-ensemble resolvents and to its asymptotics in
the limit of large dimensions (both external and intermediate) taken
asymmetrically in terms of the deformation epsilon-parameters. The
next-to-leading term in the asymptotics defines the generating differential in
the Bohr-Sommerfeld representation of the one-parameter deformed Seiberg-Witten
prepotentials (whose full two-parameter deformation leads to Nekrasov
functions). This generating differential is also shown to be the one-parameter
version of the single-point resolvent for the corresponding beta-ensemble, and
its periods in the perturbative limit of the gauge theory are expressed through
the ratios of the Harish-Chandra function. The Shr\"odinger/Baxter equations,
considered earlier in this context, directly follow from the differential
equations for the degenerate conformal block. This provides a powerful method
for evaluation of the single-deformed prepotentials, and even for the
Seiberg-Witten prepotentials themselves. We mostly concentrate on the
representative case of the insertion into the four-point block on sphere and
one-point block on torus.
11/2010;
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ABSTRACT: The AGT relations allow to convert the Zamolodchikov asymptotic formula for conformal block into the instanton expansion of the Seiberg-Witten prepotential for the theory with two colors and four fundamental flavors. This provides an explicit formula for the instanton corrections in this model. The answer is especially elegant for vanishing matter masses, then the bare charge of gauge theory q0 = eiπτ0 plays the role of a branch point on the spectral elliptic curve. The exact prepotential at this point is = (1/2πi)a2log q with q≠q0, unlike the case of another conformal theory, with massless adjoint field. Instead, 16q0 = θ104/θ004(q) = 16q(1+O(q)), i.e. the Zamolodchikov asymptotic formula gives rise, in particular, to an exact non-perturbative beta-function so that the effective coupling differs from the bare charge by infinite number of instantonic corrections.
Journal of High Energy Physics 11/2009; 2009(11):048. · 5.83 Impact Factor
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ABSTRACT: The AGT relations allow one to convert the Zamolodchikov asymptotic formula for the conformal block into the instanton expansion of the Seiberg-Witten prepotential for theory with two colors and four fundamental flavors. This provides an explicit formula for the instanton corrections in this model, resolving in this way an old problem in Seiberg-Witten theory. The answer is especially elegant for vanishing matter masses, then the bare charge of gauge theory 16q_0 = 16e^{i\pi\tau_0} plays the role of a branch point on the spectral torus. The exact prepotential at this point is F a^2\log q with q\neq q_0, unlike the case of another conformal theory, with massless adjoint field. Instead, 16q_0 = \theta_{10}^4/\theta_{00}^4(q) = 16q(1+O(q)), i.e. the Zamolodchikov asymptotics gives rise, in particular, to an exact non-perturbative beta-function so that the effective coupling differs from the bare charge by infinite number of instantonic corrections. Comment: 11 pages
09/2009;
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ABSTRACT: In a recent paper (arXiv:0906.3219) the representation of Nekrasov partition function in terms of nontrivial two-dimensional conformal field theory has been suggested. For non-vanishing value of the deformation parameter \epsilon=\epsilon_1+\epsilon_2 the instanton partition function is identified with a conformal block of Liouville theory with the central charge c = 1+ 6\epsilon^2/\epsilon_1\epsilon_2. If reversed, this observation means that the universal part of conformal blocks, which is the same for all two-dimensional conformal theories with non-degenerate Virasoro representations, possesses a non-trivial decomposition into sum over sets of the Young diagrams, different from the natural decomposition studied in conformal field theory. We provide some details about this intriguing new development in the simplest case of the four-point correlation functions. Comment: 22 pages
07/2009;
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ABSTRACT: We present a generic derivation of the WDVV equations for 6d Seiberg–Witten theory, and extend it to the families of bi-elliptic
spectral curves. We find that the elliptization of the naive perturbative and nonperturbative 6d systems roughly “doubles”
the number of moduli describing the system.
Acta Applicandae Mathematicae 11/2007; 99(3):223-244. · 0.90 Impact Factor
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ABSTRACT: We study the integrable structure of the Dirichlet boundary problem in two dimensions and extend the approach to the case of planar multiply-connected domains. The solution to the Dirichlet boundary problem in the multiply-connected case is given through a quasiclassical tau-function, which generalizes the tau-function of the dispersionless Toda hierarchy. It is shown to obey an infinite hierarchy of Hirota-like equations which directly follow from properties of the Dirichlet Green function and from the Fay identities. The relation to multi-support solutions of matrix models is briefly discussed.
Communications in Mathematical Physics 09/2005; 259(1):1-44. · 1.94 Impact Factor
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ABSTRACT: We review the integrable structure of the Dirichlet boundary problem in two dimensions. The solution to the Dirichlet boundary problem for simply-connected case is given through a quasiclassical tau-function, which satisfies the Hirota equations of the dispersionless Toda hierarchy, following from properties of the Dirichlet Green function. We also outline a possible generalization to the case of multiply-connected domains related to the multi-support solutions of matrix models.
06/2003;
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ABSTRACT: We discuss the associativity or WDVV equations and demonstrate that they can be rewritten as certain functional relations between the second derivatives of a single function, similar to the dispersionless Hirota equations. The properties of these functional relations are further discussed.
Physics Letters B. 05/2002;
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ABSTRACT: We study how the solution of the two-dimensional Dirichlet boundary problem for smooth simply connected domains depends upon variations of the data of the problem. We show that the Hadamard formula for the variation of the Dirichlet Green function under deformations of the domain reveals an integrable structure. The independent variables corresponding to the infinite set of commuting flows are identified with harmonic moments of the domain. The solution to the Dirichlet boundary problem is expressed through the tau-function of the dispersionless Toda hierarchy. We also discuss a degenerate case of the Dirichlet problem on the plane with a gap. In this case the tau-function is identical to the partition function of the planar large $N$ limit of the Hermitean one-matrix model. Comment: 25 pages, 2 figures, LaTeX
09/2001;
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ABSTRACT: We discuss the origin of the associativity (WDVV) equations in the context of quasiclassical or Whitham hierarchies. The associativity equations are shown to be encoded in the dispersionless limit of the Hirota equations for KP and Toda hierarchies. We show, therefore, that any tau-function of dispersionless KP or Toda hierarchy provides a solution to associativity equations. In general, they depend on infinitely many variables. We also discuss the particular solution to the dispersionless Toda hierarchy that describes conformal mappings and construct a family of new solutions to the WDVV equations depending on finite number of variables.
Physics Letters B. 05/2001;
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ABSTRACT: We consider the singular phases of the smooth finite-gap integrable systems arising in the context of Seiberg-Witten theory. These degenerate limits correspond to the weak and strong coupling regimes of SUSY gauge theories. The spectral curves in such limits acquire simpler forms: in most cases they become rational, and the corresponding expressions for coupling constants and superpotentials can be computed explicitly. We verify that in accordance with the computations from quantum field theory, the weak-coupling limit gives rise to precisely the "trigonometric" family of Calogero-Moser and open Toda models, while the strong-coupling limit corresponds to the solitonic degenerations of the finite-gap solutions. The formulae arising provide some new insights into the corresponding phenomena in SUSY gauge theories. Some open conjectures have been proven. Comment: 34 Pages, LaTeX, some typos and reference added
09/2000;
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ABSTRACT: We construct a two-parameter family of 2-particle Hamiltonians closed under the duality operation of interchanging the (relative) momentum and coordinate. Both coordinate and momentum dependence are elliptic, and the modulus of the momentum torus is a non-trivial function of the coordinate. This model contains as limiting cases the standard Ruijsenaars–Calogero and Toda family of Hamiltonians, which are at most elliptic in the coordinates, but not in the momenta.
Nuclear Physics B. 06/1999;
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ABSTRACT: The compactification of five-dimensional N = 2 SUSY Yang-Mills (YM) theory onto a circle provides a four-dimensional YM model with N = 4 SUSY. This supersymmetry can be broken down to N = 2 if non-trivial boundary conditions in the compact dimension, φ(x5 + R) = e2πiεφ(x5), are imposed on half of the fields. This two-parameter (R, ε) family of compactifications includes as particular limits most of the previously studied four-dimensional N = 2 SUSY YM models with supermultiplets in the adjoint representation of the gauge group. The finite-dimensional integrable system associated to these theories via the Seiberg-Witten construction is the generic elliptic Ruijsenaars-Schneider model. In particular the perturbative (weak coupling) limit is described by the trigonometric Ruijsenaars-Schneider model.
Nuclear Physics B. 02/1999;
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ABSTRACT: The prepotential and spectral curve are described for a smooth interpolation between an enlarged N=4 SUSY and ordinary N=2 SUSY Yang-Mills theory in four dimensions, obtained by compactification from five dimensions with non-trivial (periodic and antiperiodic) boundary conditions. This system provides a new solution to the generalized WDVV equations. We show that this exhausts all possible solutions of a given functional form.
Physics Letters B. 12/1998;
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ABSTRACT: We briefly review the Whitham hierarchies and their applications to integrable systems of the Seiberg-Witten type. The simplest example of the N=2 supersymmetric SU(2) pure gauge theory is considered in detail and the corresponding Whitham solutions are found explicitely.
10/1998;
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ABSTRACT: We consider 4d and 5d N=2 supersymmetric theories and demonstrate that in general their Seiberg-Witten prepotentials satisfy the Witten-Dijkgraaf-Verlinde-Verlinde (WDVV) equations. General proof for the Yang-Mills models (with matter in the first fundamental representation) makes use of the hyperelliptic curves and underlying integrable systems. A wide class of examples is discussed, it contains few understandable exceptions. In particular, in perturbative regime of 5d theories in addition to naive field theory expectations some extra terms appear, like it happens in heterotic string models. We consider also the example of the Yang-Mills theory with matter hypermultiplet in the adjoint representation (related to the elliptic Calogero-Moser system) when the standard WDVV equations do not hold. Comment: LaTeX, 40 pages, no figures
01/1997;
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ABSTRACT: We discuss the construction of the spectral curve and the action integrals for the ``elliptic" $XYZ$ spin chain of the length $N_c$. Our analysis can reflect the integrable structure behind the ``elliptic" ${\cal N}=2$ supersymmetric QCD with $N_f=2N_c$.
05/1996;
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ABSTRACT: In the series of papers we represent the ``Whittaker'' wave functional of $d+1$-dimensional Liouville model as a correlator in $d+0$-dimensional theory of the sine-Gordon type (for $d=0$ and $1$). Asypmtotics of this wave function is characterized by the Harish-Chandra function, which is shown to be a product of simple $\Gamma$-function factors over all positive roots of the corresponding algebras (finite-dimensional for $d=0$ and affine for $d=1$). This is in nice correspondence with the recent results on 2- and 3-point correlators in $1+1$ Liouville model, where emergence of peculiar double-periodicity is observed. The Whittaker wave functions of $d+1$-dimensional non-affine ("conformal") Toda type models are given by simple averages in the $d+0$ dimensional theories of the affine Toda type. This phenomenon is in obvious parallel with representation of the free-field wave functional, which is originally a Gaussian integral over interior of a $d+1$-dimensional disk with given boundary conditions, as a (non-local) quadratic integral over the $d$-dimensional boundary itself. In the present paper we mostly concentrate on the finite-dimensional case. The results for finite-dimensional "Iwasawa" Whittaker functions were known, and we present their survey. We also construct new "Gauss" Whittaker functions.
03/1996;
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ABSTRACT: The third Poisson structure of KdV equation in terms of canonical ``free fields'' and reduced WZNW model is discussed. We prove that it is ``diagonalized'' in the Lagrange variables which were used before in formulation of 2D gravity. We propose a quantum path integral for KdV equation based on this representation. Comment: 6pp, Latex. to appear in ``Proceedings of V conference on Mathematical Physics, String Theory and Quantum Gravity, Alushta, June 1994'' Teor.Mat.Fiz. 1995
03/1995;
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ABSTRACT: We consider the canonical quantization scheme for $c \leq 1$ ($(p,q)$ -) string theories and compare it with what is known from matrix model approach. We derive explicitly a trivial ($\equiv $ topological) solution. We discuss a ``dressing" operator which in principle allows one to obtain a non-trivial solution, but an explicit computation runs into a problem of analytic continuation of the formal expressions for $\tau $-functions. We discuss also the application of proposed scheme to the case of discrete matrix model and consider some parallels with mirror symmetry and background independence in string theory.
02/1994;
