Thu, 03 Nov 2022

15:00 - 16:00
L5

Model-theoretic Algebraic Closure in Zilber’s Field

Vahagn Aslanyan
(Leeds University)
Abstract

I will explain how the model-theoretic algebraic closure in Zilber’s pseudo-exponential field can be described in terms of the self-sufficient closure. I will sketch a proof and show how the Mordell-Lang conjecture for algebraic tori comes into play. If time permits, I’ll also talk about the characterisation of strongly minimal sets and their geometries. This is joint work (still in progress) with Jonathan Kirby.

Mon, 10 Oct 2022
16:00
L6

Modular forms, Galois representations, and cohomology of line bundles

Aleksander Horawa
Abstract

Modular forms are holomorphic functions on the upper half plane satisfying a transformation property under the action of Mobius transformations. While they are a priori complex-analytic objects, they have applications to number theory thanks to their connection with Galois representations. Weight one modular forms are special because their Galois representations factor through a finite quotient. In this talk, we will explain a different degeneracy: they contribute to the cohomology of a line bundle over the modular curve in degrees 0 and 1. We propose an arithmetic explanation for this: an action of a unit group associated to the Galois representation of the modular form. This extends the conjectures of Venkatesh, Prasanna, and Harris. Time permitting, we will discuss a generalization to Hilbert modular forms.

The signature and cusp geometry of hyperbolic knots
Davies, A Juhasz, A Lackenby, M Tomasev, N Geometry and Topology
The signature and cusp geometry of hyperbolic knots
Davies, A Juhasz, A Lackenby, M Tomasev, N Geometry and Topology volume 28 issue 2024 2313-2343 (24 Aug 2024)
Mon, 30 Jan 2023
13:00
L1

Double holography and Page curves in Type IIB

Christoph Uhlemann
(Oxford )
Abstract

In recent progress on the black hole information paradox, Page curves consistent with unitarity have been obtained in 2d models and in bottom-up braneworld models using the notion of double holography. In this talk we discuss top-down models realizing 4d black holes coupled to a bath in Type IIB string theory and obtain Page curves. We make the ideas behind double holography precise in these models and address causality puzzles which have arisen in the bottom-up models, leading to a refinement of their interpretation.
 

Mon, 23 Jan 2023
13:00
L1

Higgsing SCFTs in d=3,4,5,6

Zhenghao Zhong
(Oxford )
Abstract

We study supersymmetric gauge theories with 8 supercharges in d=3,4,5,6. For these theories, one can perform Higgsings by turning on VEVs of scalar fields. However, this process can often be difficult when dealing with superconformal field theories (SCFTs) where the Lagrangian is often not known. Using techniques of magnetic quivers and a new algorithm we call "Inverted Quiver Subtraction", we show how one can easily obtain the SCFT(s) after Higgsing. This technique can be equally well applied to SCFTs in d=3,4,5,6. 

Mon, 16 Jan 2023
13:00
L1

1d sectors from the squashed three-sphere

Pieter Bomans
(Oxford )
Further Information

3d N=4 SCFTs contain a 1d topological sector of twisted linear
combinations of half-BPS local operators inserted along a line. I will
explain how to construct analogous 1d topological sectors on the
three-sphere and in particular show how these sectors are preserved under
the squashing of the sphere. Furthermore, I will show how to introduce FI
parameters and real masses in the 3d N=4 theory and demonstrate how such
deformations can be translated in universal deformations of the
corresponding 1d theory. Finally, I will discuss a series of applications
and future prospects.

Mon, 07 Nov 2022
13:00
L1

The holographic duals of Argyres--Douglas theories

Christopher Couzens
(Oxford )
Abstract

Argyres—Douglas (AD) theories are 4d N=2 SCFTs which have some unusual features, and until recently, explicit holographic duals of these theories were unknown. We will consider a concrete class of these theories obtained by wrapping the 6d N=(2,0) ADE theories on a (twice) punctured sphere: one irregular and one regular puncture, and construct their holographic duals. The novel aspects of these solutions require a relaxation of the regularity conditions of the usual Gaiotto—Maldacena framework and to allow for brane singularities. We show how to construct the dictionary between the AdS(5) solutions and the field theory and match observables between the two. If time allows, I will comment on some on-going work about further compactifying the AD theories on spindles, or the 6d theories on four-dimensional orbifolds. 

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