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.
2026-02-24 (Wtorek)
Zapraszamy do sali 2.22, ul. Pasteura 5 o godzinie 12:15  Calendar icon
Francis Bonahon (University of Southern California and Michigan State University)

Transparent SL_n-skeins

For a Lie group G, the G-skein module of a 3-dimensional manifold M is a fundamental object in Witten’s interpretation of quantum knot invariants in the framework of a topological quantum field theory. Its elements are represented by knots colored by representations of G. This construction depends on a parameter q and, when this parameter q is a root of unity, the G-skein module contains elements with a surprising “transparency” property, in the sense that they can be traversed by any other skein without changing the resulting total skein. I will describe some (and conjecturally all) of these transparent elements in the case of the special linear group SL_n.