Schubert varieties and the fusion products

For each $A\in\N^n$ we define a Schubert variety $\sh_A$ as a closure of the \Slt(\C[t])-orbit in the projectivization of the fusion product $M^A$. We clarify the connection of the geometry of the Schubert varieties with an algebraic structure of $M^A$ as \slt\otimes\C[t] modules. In the case when all the entries of $A$ are different $\sh_A$ is smooth projective algebraic variety. We study its geometric properties: the Lie algebra of the vector fields, the coordinate ring, the cohomologies of the line bundles. We also prove, that the fusion products can be realized as the dual spaces of the sections of these bundles.Comment: 34 page

Two character formulas for sl2^\hat{sl_2} spaces of coinvariants

We consider $\hat{sl_2}$ spaces of coinvariants with respect to two kinds of ideals of the enveloping algebra U(sl_2\otimes\C[t]). The first one is generated by $sl_2\otimes t^N$, and the second one is generated by $e\otimes P(t), f\otimes R(t)$ where $P(t), R(t)$ are fixed generic polynomials. (We also treat a generalization of the latter.) Using a method developed in our previous paper, we give new fermionic formulas for their Hilbert polynomials in terms of the level-restricted Kostka polynomials and $q$-multinomial symbols. As a byproduct, we obtain a fermionic formula for the fusion product of $sl_3$-modules with rectangular highest weights, generalizing a known result for symmetric (or anti-symmetric) tensors.Comment: LaTeX, 22 pages; very minor change

VOA[MM_4]

We take a peek at a general program that associates vertex (or, chiral) algebras to smooth 4-manifolds in such a way that operations on algebras mirror gluing operations on 4-manifolds and, furthermore, equivalent constructions of 4-manifolds give rise to equivalences (dualities) of the corresponding algebras

Super Liouville conformal blocks from N=2 SU(2) quiver gauge theories

The conjecture about the correspondence between instanton partition functions in the N=2 SUSY Yang-Mills theory and conformal blocks of two-dimensional conformal field theories is extended to the case of the N=1 supersymmetric conformal blocks. We find that the necessary modification of the moduli space of instantons requires additional restriction of Z(2)-symmetry. This leads to an explicit form of the N=1 superconformal blocks in terms of Young diagrams with two sorts of cells.Comment: 18 pages, misprints corrected, formula 5.8 is improved, references adde