Wydział Fizyki UW > Badania > Seminaria i konwersatoria > String Theory Journal Club
2026-04-01 (Środa)
Zapraszamy do sali 2.23, ul. Pasteura 5 o godzinie 14:15  Calendar icon
Gaetan Borot (Humboldt University)

Large N expansions for random partitions via Nekrasov equations

It is well-known that matrix models admit topological expansions as the size goes to infinity, that the asymptotic expansion to all-order can be determined from loop equations (Virasoro constraints) and take the form of Eynard-Orantin topological recursion. I will show how to a similar approach can be used (not only formally, but also rigorously) for random matrix models with discrete eigenvalues or models of random partitions. Loop equations are replaced by "non-perturbative Dyson-Schwinger equations" similar to those Nekrasov derived in 4d N = 2 supersymmetric gauge theories, there is a topological recursion but it is different from Eynard-Orantin one beyond the leading order. I will discuss application to random lozenge tilings on surfaces and the Kenyon-Okounkov conjecture (fluctuations are described by free bosonic field). Based on https://arxiv.org/abs/2601.16377 with Vadim Gorin and Alice Guionnet.
2026-03-10 (Wtorek)
Zapraszamy do sali 2.22, ul. Pasteura 5 o godzinie 12:15  Calendar icon
Yegor Zenkevich (University of Edinburgh)

Framed wall-crossing in super-Yang-Mills theory and quantum toroidal algebras

I will demonstrate that wall-crossing behaviour of framed BPS states in N=4 and N=2 four-dimensional supersymmetric gauge theories can be described using a new and powerful algebraic formalism. In particular, I show that the algebra of line operators is given by the image of the "universal" algebra (quantum affine or quantum toroidal) in a tensor product of certain particularly simple representations thereof. The action of the "universal" algebra on the tensor product requires the choice of the coproduct, which turns out not to be unique, but is parametrized by chambers in the moduli space of the gauge theory. Different choices of coproduct are related by Drinfeld twists, each given by the product of certain elementary twists corresponding to walls of the second kind in the moduli space. The Kontsevich-Soibelman spectrum generator is then given by the R-matrix of the "universal" algebra.