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University of York Geometry, Analysis and Mathematical Physics seminar 2025-26

All are welcome to attend the seminar, which usually takes place at 2:30pm on Tuesdays in the Topos during term time. (Directions to the Topos)

Autumn Semester 2025

DateSpeakerTitle
23 September
30 SeptemberAmihay Hanany (Imperial)Symplectic singularities, Magnetic quivers, and Hasse diagrams
7 OctoberJiajun Yan (Rice)A gauge-theoretic construction of 4-dimensional hyperkähler ALE spaces
14 OctoberDerek Harland (Leeds)The BF Lagrangian 1-form and the Hitchin system
4 NovemberMathew Bullimore (Durham)TBA
11 NovemberTom Bridgeland (Sheffield)TBA
18 NovemberDaan Janssen (York)TBA
25 NovemberYizhi Wang (York)TBA
2 DecemberJason Lotay (Oxford)TBA
9 DecemberLinden Disney-Hogg (Leeds)TBA

Spring Semester 2026

DateSpeakerTitle
10 February
17 February
24 February
3 March
10 March
17 March
24 March
14 April
21 April
28 April

Previous years' seminars

2024-25
2023-24
2022-23
2021-22
2020-21
2019-20


Abstracts

30 September. Amihay Hanany (Imperial)
Title. Symplectic singularities, Magnetic quivers, and Hasse diagrams
Abstract. Symplectic singularities fall into classes of different types: Klein/duVal singularities, Moduli spaces of instantons, Nilpotent orbits, Intersection of orbits and Słodowy slices, Slices in the affine Grassmanian, and more. They are of interest in both mathematics and physics. Their construction could be
  1. in algebraic settings, like in the study of nilpotent orbits.
  2. Higgs branch of a supersymmetric gauge theory with 8 supercharges - this is sometimes called HyperKähler quotient, sometimes Hamiltonian reduction.
  3. Coulomb branch of a 3d N=4 supersymmetric gauge theory - I prefer to call it magnetic quiver and drop the long name.
Quivers play a crucial role in the construction, going back to the work of Kraft and Procesi '79, proceeding with many contributions over the years. Many quivers appear naturally in superstring theory, with or without brane constructions. This leads to great physical insights on the behavior of symplectic singularities. Some of the phenomena go under the name "3d mirror symmetry" and "symplectic duality".

7 October. Jiajun Yan (Rice)
Title. A gauge-theoretic construction of 4-dimensional hyperkähler ALE spaces
Abstract. Non-compact hyperkähler spaces arise frequently in gauge theory. The 4-dimensional hyperkähler ALE spaces are a special class of complete non-compact hyperkähler spaces. They are in one-to-one correspondence with the finite subgroups of SU(2) and have interesting connections with representation theory and singularity theory, captured by the McKay Correspondence.
In this talk, we give a gauge-theoretic construction of these spaces, inspired by Kronheimer’s original construction via a finite-dimensional hyperkähler reduction. In the gauge-theoretic construction, we realize each ALE space as a moduli space of solutions to a system of equations for a pair consisting of a connection and a section of a vector bundle over an orbifold Riemann surface, modulo a hyperkähler gauge group action.

14 October. Derek Harland (Leeds)
Title. The BF Lagrangian 1-form and the Hitchin system
Abstract. TBA

4 November. Mathew Bullimore (Durham)
Title. TBA
Abstract. TBA

11 November. Tom Bridgeland (Sheffield)
Title. TBA
Abstract. TBA

18 November. Daan Janssen (York)
Title. TBA
Abstract. TBA

25 November. Yizhi Wang (York)
Title. TBA
Abstract. TBA

2 December. Jason Lotay (Oxford)
Title. TBA
Abstract. TBA

9 December. Linden Disney-Hogg (Leeds)
Title. TBA
Abstract. TBA

Last updated 1 October, 2025

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