arXiv subjects

Sh. Shakirov

Publications and source records attributed to Sh. Shakirov.

At least 19 recordsLinked to original sources

arXiv2026

Correlators in the theory of Integral Discriminants

Integral discriminants provide a simple and fundamental model for non-Gaussian integrals, associated with homogeneous polynomials of degree r in n variables. We argue that, in this context, the study of correlators is equally if not more important. In this paper, we study a natural class of correlators in this model -- the invariant correlators. We suggest a general method to compute invariant correlators using differential operators that act on the partition function. This method allows to compute general invariant correlators in terms of the fundamental invariants. Moreover, in some cases the correlators appear to be simply polynomials in the invariants. This could be an interesting manifestation of superintegrability phenomenon in the theory of integral discriminants.

hep-th↗

arXiv2025

5D AGT conjecture for circular quivers

The best way to represent generic conformal blocks is provided by the free-field formalism, where they acquire a form of multiple Dotsenko-Fateev-like integrals of the screening operators. Degenerate conformal blocks can be described by the same integrals with special choice of parameters. Integrals satisfy various recurrent relations, which for the special choice of parameters reduce to closed equations. This setting is widely used in explaining the AGT relation, because similar integral representations exist also for Nekrasov functions. We extend this approach to the case of q-Virasoro conformal blocks on elliptic surface -- generic and degenerate. For the generic case, we check equivalence with instanton partition function of a 5d circular quiver gauge theory. For the degenerate case, we check equivalence with partition function of a defect in the same theory, also known as the Shiraishi function. We find agreement in both cases. This opens a way to re-derive the sophisticated equation for the Shiraishi function as the equation for the corresponding integral, what seems straightforward, but remains technically involved and is left for the future.

hep-th↗

arXiv2025

Cauchy identities for genus 2 Schur polynomials

Genus 2 Macdonald polynomials $\Psi^{(q,t)}_{j_1,j_2,j_3}$ generalize ordinary Macdonald polynomials in several aspects. First, they provide common eigenfunctions for commuting difference operators that generalize the Macdonald difference operators of type $A_1$. Second, the algebra generated by these difference operators together with multiplication operators admits an action of genus 2 mapping class group (MCG) that generalizes the well-known action of $SL(2,{\mathbb Z})$ for ordinary Macdonald polynomials. In this paper, one more important aspect of Macdonald theory is considered: the Cauchy identities. We construct a genus 2 generalization of Cauchy identities in the particular case when $t=q=1$, i.e. for genus 2 Schur polynomials.

math.RT↗

arXiv2024

Deformation of superintegrability in the Miwa-deformed Gaussian matrix model

We consider an arbitrary deformation of the Gaussian matrix model parameterized by Miwa variables $z_a$. One can look at it as a mixture of the Gaussian and logarithmic (Selberg) potentials, which are both superintegrable. The mixture is not, still one can find an explicit expression for an arbitrary Schur average as a linear transform of a {\it finite degree} polynomial made from the values of skew Schur functions at the Gaussian locus $p_k=\delta_{k,2}$. This linear operation includes multiplication with an exponential $ e^{z_a^2/2}$ and a kind of Borel transform of the resulting product, which we call multiple and enhanced. The existence of such remarkable formulas appears intimately related to the theory of auxiliary $K$-polynomials, which appeared in {\it bilinear} superintegrable correlators at the Gaussian point (strict superintegrability). We also consider in the very detail the generating function of correlators $<(\Tr X)^k>$ in this model, and discuss its integrable determinant representation. At last, we describe deformation of all results to the Gaussian $\beta$-ensemble.

hep-th↗

arXiv2024

Summing up perturbation series around superintegrable point

We work out explicit formulas for correlators in the Gaussian matrix model perturbed by a logarithmic potential, i.e. by inserting Miwa variables. In this paper, we concentrate on the example of a single Miwa variable. The ordinary Gaussian model is superintegrable, i.e. the average of the Schur functions $S_Q$ is an explicit function of the Young diagram $Q$. The question is what happens to this property after perturbation. We show that the entire perturbation series can be nicely summed up into a kind of Borel transform of a universal exponential function, while the dependence on $R$ enters through a polynomial factor in front of this exponential. Moreover, these polynomials can be described explicitly through a single additional structure, which we call ``truncation'' of the Young diagram $Q$. It is unclear if one can call this an extended superintegrability, but at least it is a tremendously simple deformation of it. Moreover, the vanishing Gaussian correlators remain vanishing and, hence, are not deformed at all.

hep-th↗

arXiv2023

An Elliptic Generalization of $A_1$ Spherical DAHA at $K=2$

We construct an algebra that is an elliptic generalization of $A_1$ spherical DAHA acting on its finite-dimensional module at $t=-q^{-K/2}$ with $K=2$. We prove that $PSL(2,\mathbb Z)$ acts by automorphisms of the algebra we constructed, and provide an explicit representation of automorphisms and algebra operators alike by $3\times 3$ matrices of elliptic functions. A relation of this construction to the K-theory character of affine Laumon space is conjectured. We point out two potential applications, respectively to $SL(3,\mathbb Z)$ symmetry of Felder-Varchenko functions and to new elliptic invariants of torus knots and Seifert manifolds.

math.QA↗

arXiv2021

Quantum Racah matrices and 3-strand braids in representation [3,3]

This paper is a next step in the project of systematic description of colored knot polynomials started in arXiv:1506.00339. In this paper, we managed to explicitly find the $\textit{inclusive}$ Racah matrices, i.e. the whole set of mixing matrices in channels $R^{\otimes 3}\longrightarrow Q$ with all possible $Q$, for $R=[3,3]$. The case $R=[3,3]$ is a multiplicity free case as well as $R=[2,2]$ obtained in arXiv:1605.03098. The calculation is made possible by the use of highest weight method with the help of Gelfand-Tseitlin tables. The result allows one to evaluate and investigate $[3,3]$-colored polynomials for arbitrary 3-strand knots, and this confirms many previous conjectures on various factorizations, universality, and differential expansions. With the help of a method developed in arXiv:1605.04881 we manage to calculate {\it exclusive} Racah matrices $S$ and $\bar S$ in $R=[3,3]$. Our results confirm a calculation of these matrices in arXiv:1606.06015, which was based on the conjecture of explicit form of differential expansion for twist knots. Explicit answers for Racah matrices and $[3,3]$-colored polynomials for 3-strand knots up to 10 crossings are available at http://knotebook.org.

hep-th↗

arXiv2018

On (q,t)-deformation of Gaussian matrix model

The recently discovered general formulas for perturbative correlators in basic matrix models can be interpreted as the Schur-preservation property of Gaussian measures. Then substitution of Schur by, say, Macdonald polynomials, defines a q,t-deformation of the matrix model. Eigenvalue integral representations and Virasoro-like constraints are immediate consequences.

hep-th↗

arXiv2017

On the block structure of the quantum R-matrix in the three-strand braids

Quantum $\mathcal{R}$-matrices are the building blocks for the colored HOMFLY polynomials. In the case of three-strand braids with an identical finite-dimensional irreducible representation $T$ of $SU_q(N)$ associated with each strand one needs two matrices: $\mathcal{R}_1$ and $\mathcal{R}_2$. They are related by the Racah matrices $\mathcal{R}_2 = \mathcal{U} \mathcal{R}_1 \mathcal{U}^{\dagger}$. Since we can always choose the basis so that $\mathcal{R}_1$ is diagonal, the problem is reduced to evaluation of $\mathcal{R}_2$-matrices. This paper is one more step on the road to simplification of such calculations. We found out and proved for some cases that $\mathcal{R}_2$-matrices could be transformed into a block-diagonal ones. The essential condition is that there is a pair of accidentally coinciding eigenvalues among eigenvalues of $\mathcal{R}_1$-matrix. The angle of the rotation in the sectors corresponding to accidentally coinciding eigenvalues from the basis defined by the Racah matrix to the basis in which $\mathcal{R}_2$ is block-diagonal is $\pm \fracπ{4}$.

hep-th↗

arXiv2017

Genus Two Generalization of $A_1$ spherical DAHA

We consider a system of three commuting difference operators in three variables $x_{12},x_{13},x_{23}$ with two generic complex parameters $q,t$. This system and its eigenfunctions generalize the trigonometric $A_1$ Ruijsenaars-Schneider model and $A_1$ Macdonald polynomials, respectively. The principal object of study in this paper is the algebra generated by these difference operators together with operators of multiplication by $x_{ij} + x_{ij}^{-1}$. We represent the Dehn twists by outer automorphisms of this algebra and prove that these automorphisms satisfy all relations of the mapping class group of the closed genus two surface. Therefore we argue from topological perspective this algebra is a genus two generalization of $A_1$ spherical DAHA.

math.QA↗

arXiv2013

Colored knot amplitudes and Hall-Littlewood polynomials

The amplitudes of refined Chern-Simons (CS) theory, colored by antisymmetric (or symmetric) representations, conjecturally generate the Lambda^r- (or S^r-) colored triply graded homology of (n,m) torus knots. This paper is devoted to the generalization of Rosso-Jones formula to refined amplitudes, that involves non-trivial Gamma-factors -- expansion coefficients in the Macdonald basis. We derive from refined CS theory a linear recursion w.r.t. transformations (n,m) -> (n, n+m) and (n,m) -> (m,-n) that fully determines these factors. Applying this recursion to (n,nk+1) torus knots colored by antisymmetric representations [1^r] we prove that their amplitudes are rectangular [n^r] Hall-Littlewood polynomials under k units of framing (a.k.a. the Bergeron-Garsia nabla) operator. For symmetric representations [r], we find the dual -- q-Whittaker -- polynomials. These results confirm and give a colored extension of the observation of arXiv:1201.3339 that triply graded homology of many torus knots has a strikingly simple description in terms of Hall-Littlewood polynomials.

math-ph↗

arXiv2013

On Undulation Invariants of Plane Curves

One of the general problems in algebraic geometry is to determine algorithmically whether or not a given geometric object, defined by explicit polynomial equations (e.g. a curve or a surface), satisfies a given property (e.g. has singularities or other distinctive features of interest). A classical example of such a problem, described by A.Cayley and G.Salmon in 1852, is to determine whether or not a given plane curve of degree r > 3 has undulation points -- the points where the tangent line meets the curve with multiplicity four. They proved that there exists an invariant of degree 6(r - 3)(3 r - 2) that vanishes if and only if the curve has undulation points. In this paper we give explicit formulae for this invariant in the case of quartics (r=4) and quintics (r=5), expressing it as the determinant of a matrix with polynomial entries, of sizes 21 times 21 and 36 times 36 respectively.

math.AG↗

arXiv2012

Torus HOMFLY as the Hall-Littlewood Polynomials

We show that the HOMFLY polynomials for torus knots T[m,n] in all fundamental representations are equal to the Hall-Littlewood polynomials in representation which depends on m, and with quantum parameter, which depends on n. This makes the long-anticipated interpretation of Wilson averages in 3d Chern-Simons theory as characters precise, at least for the torus knots, and calls for further studies in this direction. This fact is deeply related to Hall-Littlewood-MacDonald duality of character expansion of superpolynomials found in arXiv:1201.3339. In fact, the relation continues to hold for extended polynomials, but the symmetry between m and n is broken, then m is the number of strands in the braid. Besides the HOMFLY case with q=t, the torus superpolynomials are reduced to the single Hall-Littlewood characters in the two other distinguished cases: q=0 and t=0.

hep-th↗

arXiv2012

Interplay between MacDonald and Hall-Littlewood expansions of extended torus superpolynomials

In arXiv:1106.4305 extended superpolynomials were introduced for the torus links T[m,mk+r], which are functions on the entire space of time variables and, at expense of reducing the topological invariance, possess additional algebraic properties, resembling those of the matrix model partition functions and the KP/Toda tau-functions. Not surprisingly, being a suitable extension it actually allows one to calculate the superpolynomials. These functions are defined as expansions into MacDonald polynomials, and their dependence on k is entirely captured by the action of the cut-and-join operator, like in the HOMFLY case. We suggest a simple description of the coefficients in these character expansions, by expanding the initial (at k=0) conditions for the k-evolution into the new auxiliary basis, this time provided by the Hall-Littlewood polynomials, which, hence, play a role in the description of the dual m-evolution. For illustration we list manifest expressions for a few first series, mk\pm 1, mk\pm 2, mk\pm 3, mk\pm 4. Actually all formulas were explicitly tested up to m=17 strands in the braid.

hep-th↗

arXiv2011

Resolvents and Seiberg-Witten representation for Gaussian beta-ensemble

The exact free energy of matrix model always obeys the Seiberg-Witten (SW) equations on a complex curve defined by singularities of the quasiclassical resolvent. The role of SW differential is played by the exact one-point resolvent. We show that these properties are preserved in generalization of matrix models to beta-ensembles. However, since the integrability and Harer-Zagier topological recursion are still unavailable for beta-ensembles, we need to rely upon the ordinary AMM/EO recursion to evaluate the first terms of the genus expansion. Consideration in this paper is restricted to the Gaussian model.

hep-th↗

arXiv2011

Proving AGT conjecture as HS duality: extension to five dimensions

We extend the proof from arXiv:1012.3137, which interprets the AGT relation as the Hubbard-Stratonovich duality relation to the case of 5d gauge theories. This involves an additional q-deformation. Not surprisingly, the extension turns out to be trivial: it is enough to substitute all relevant numbers by q-numbers in all the formulas, Dotsenko-Fateev integrals by the Jackson sums and the Jack polynomials by the MacDonald ones. The problem with extra poles in individual Nekrasov functions continues to exist, therefore, such a proof works only for β= 1, i.e. for q=t in MacDonald's notation. For β\ne 1 the conformal blocks are related in this way to a non-Nekrasov decomposition of the LMNS partition function into a double sum over Young diagrams.

hep-th↗

arXiv2010

A direct proof of AGT conjecture at beta = 1

The AGT conjecture claims an equivalence of conformal blocks in 2d CFT and sums of Nekrasov functions (instantonic sums in 4d SUSY gauge theory). The conformal blocks can be presented as Dotsenko-Fateev beta-ensembles, hence, the AGT conjecture implies the equality between Dotsenko-Fateev beta-ensembles and the Nekrasov functions. In this paper, we prove it in a particular case of beta=1 (which corresponds to c = 1 at the conformal side and to epsilon_1 + epsilon_2 = 0 at the gauge theory side) in a very direct way. The central role is played by representation of the Nekrasov functions through correlators of characters (Schur polynomials) in the Selberg matrix models. We mostly concentrate on the case of SU(2) with 4 fundamentals, the extension to other cases being straightforward. The most obscure part is extending to an arbitrary beta: for beta \neq 1, the Selberg integrals that we use do not reproduce single Nekrasov functions, but only sums of them.

hep-th↗

arXiv2010

Brezin-Gross-Witten model as "pure gauge" limit of Selberg integrals

The AGT relation identifies the Nekrasov functions for various N=2 SUSY gauge theories with the 2d conformal blocks, which possess explicit Dotsenko-Fateev matrix model (beta-ensemble) representations the latter being polylinear combinations of Selberg integrals. The "pure gauge" limit of these matrix models is, however, a non-trivial multiscaling large-N limit, which requires a separate investigation. We show that in this pure gauge limit the Selberg integrals turn into averages in a Brezin-Gross-Witten (BGW) model. Thus, the Nekrasov function for pure SU(2) theory acquires a form very much reminiscent of the AMM decomposition formula for some model X into a pair of the BGW models. At the same time, X, which still has to be found, is the pure gauge limit of the elliptic Selberg integral. Presumably, it is again a BGW model, only in the Dijkgraaf-Vafa double cut phase.

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