Tue, 05 Mar 2019
15:30
L4

How many real Artin-Tate motives are there?

Martin Gallauer
(Oxford)
Further Information

The goals of my talk are 1) to place this question within the framework of tensor-triangular geometry, and 2) to report on joint work with Paul Balmer (UCLA) which provides an answer in this framework.

Tue, 05 Feb 2019

15:30 - 16:30
L4

Generalized Polar Geometry

Sandra di Rocco
(KTH)
Abstract

Polar classes are very classical objects in Algebraic Geometry. A brief introduction to the subject will be presented and ideas and preliminarily results towards generalisations will be explained. These ideas can be applied towards variety sampling and relevant applications. 
 

Mon, 25 Feb 2019
14:15
L4

Tropically constructed Lagrangians in mirror quintic threefolds

Cheuk Yu Mak
(Cambridge University)
Abstract

In this talk, we will explain how to construct embedded closed Lagrangian submanifolds in mirror quintic threefolds using tropical curves and the toric degeneration technique. As an example, we will illustrate the construction for tropical curves that contribute to the Gromov–Witten invariant of the line class of the quintic threefold. The construction will in turn provide many homologous and non-Hamiltonian isotopic Lagrangian
rational homology spheres, and a geometric interpretation of the multiplicity of a tropical curve as the weight of a Lagrangian. This is a joint work with Helge Ruddat.

 

Mon, 04 Feb 2019
14:15
L4

Gluing methods for Vortex dynamics in Euler flows

Manuel del Pino
(Bath University)
Abstract

We consider the two-dimensional Euler flow for an incompressible fluid confined to a smooth domain. We construct smooth solutions with concentrated vorticities around $k$ points which evolve according to the Hamiltonian system for the Kirkhoff-Routh energy,  using an outer-inner solution gluing approach. The asymptotically singular profile  around each point resembles a scaled finite mass solution of Liouville's equation.
We also discuss the {\em vortex filament conjecture} for the three-dimensional case. This is joint work with Juan D\'avila, Monica Musso and Juncheng Wei.

 

Mon, 28 Jan 2019
14:15
L4

Orientation problems in 7-dimensional gauge theory

Markus Upmeier
(Oxford University)
Abstract

After discussing a general excision technique for constructing canonical orientations for moduli spaces that derive from an elliptic equation, I shall
explain how to carry out this program in the case of G2-instantons and the 7-dimensional real Dirac operator. In many ways our approach can
be regarded as a categorification of the Atiyah-Singer index theorem. (Based on joint work with Dominic Joyce.)

 

Mon, 21 Jan 2019
14:15
L4

Orientations for gauge-theoretic moduli problems

Yuuji Tanaka
(Oxford University)
Abstract

This talk is based on joint work with Dominic Joyce and Markus Upmeier. Issues we'd like to talk about are a) the orientability of moduli spaces that
appear in various gauge-theoretic problems; and b) how to orient those moduli spaces if they are orientable. We begin with briefly mentioning backgrounds and motivation, and recall basics in gauge theory such as the Atiyah-Hitchin-Singer complex and the Kuranishi model by taking the anti-self-dual instanton moduli space as an example. We then describe the orientability and canonical orientations of the anti-self-dual instanton moduli space, and other
gauge-theoretic moduli spaces which turn up in current research interests.

 

Tue, 26 Feb 2019

12:00 - 13:15
L4

Higgsplosion: excitements and problems

Alexander Belyaev
(Southampton University)
Abstract

A recent calculation of the multi-Higgs boson production in scalar theories
with spontaneous symmetry breaking has demonstrated the fast growth of the
cross section with the Higgs multiplicity at sufficiently large energies,
called “Higgsplosion”. It was argued that “Higgsplosion” solves the Higgs
hierarchy and fine-tuning problems. The phenomena looks quite exciting,
however in my talk I will present arguments that: a) the formula for
“Higgsplosion” has a limited applicability and inconsistent with unitarity
of the Standard Model; b) that the contribution from “Higgsplosion” to the
imaginary part of the Higgs boson propagator cannot be re-summed in order to
furnish a solution of the Higgs hierarchy and fine-tuning problems.

Based on our recent paper https://arxiv.org/abs/1808.05641 (A. Belyaev, F. Bezrukov, D. Ross)

 

Tue, 22 Jan 2019
14:15
L4

Generalisations of the (Pin,osp(1|2)) Howe duality

Roy Oste
(University of Ghent)
Abstract

The classical Dirac operator is part of an osp(1|2) realisation inside the Weyl-Clifford algebra which is Pin-invariant. This leads to a multiplicity-free decomposition of the space of spinor-valued polynomials in irreducible modules for this Howe dual pair. In this talk we review an abstract generalisation A of the Weyl algebra that retains a realisation of osp(1|2) and we determine its centraliser algebra explicitly. For the special case where A is a rational Cherednik algebra, the centralizer algebra provides a refinement of the previous decomposition whose analogue was no longer irreducible in general. As an example, for the  group S3 in specific, we will examine the finite-dimensional irreducible modules of the centraliser algebra.

Fri, 09 Nov 2018

12:30 - 13:00
L4

Using signatures to predict amyotrophic lateral sclerosis progression

Imanol Pérez
(University of Oxford)
Abstract

Medical data often comes in multi-modal, streamed data. The challenge is to extract useful information from this data in an environment where gathering data is expensive. In this talk, I show how signatures can be used to predict the progression of the ALS disease.

Subscribe to L4