Deconfining N=2 SCFTs
Abstract
In this talk I will describe a systematic approach, introduced in our recent work 2111.08022, to construct Lagrangian descriptions for a class of strongly interacting N=2 SCFTs. I will review the main ingredients of these constructions, namely brane tilings and the connection to gauge theories. For concreteness, I will then specialize to the case of the simplest of such geometrical setups, as in the paper, even though our approach should be much more general. I will comment on some low rank examples of the theories we built, that are well understood by (many) alternative approaches and conclude with some open questions and ideas for future directions to explore.
It is also possible to join online via Microsoft Teams.
The structure of planar graphs
Abstract
This talk is about the global structure of planar graphs and other more general graph classes. The starting point is the Lipton-Tarjan separator theorem, followed by Baker's decomposition of a planar graph into layers with bounded treewidth. I will then move onto layered treewidth, which is a more global version of Baker's decomposition. Layered treewidth is a precursor to the recent development of row treewidth, which has been the key to solving several open problems. Finally, I will describe generalisations for arbitrary minor-closed classes.
Gaussian distribution of squarefree and B-free numbers in short intervals
Abstract
As a model for the primes, in this talk I will address such statistical questions for the sequence of squarefree numbers, i.e., numbers not divisible by the square of any prime, among other related ``sifted'' sequences called B-free numbers. I hope to further motivate and explain our main result that shows, unconditionally, that short interval counts of squarefree numbers do satisfy Gaussian statistics, answering several questions of R.R. Hall.
Finite element methods for the Stokes–Onsager–Stefan–Maxwell equations of multicomponent flow
Abstract
The Onsager framework for linear irreversible thermodynamics provides a thermodynamically consistent model of mass transport in a phase consisting of multiple species, via the Stefan–Maxwell equations, but a complete description of the overall transport problem necessitates also solving the momentum equations for the flow velocity of the medium. We derive a novel nonlinear variational formulation of this coupling, called the (Navier–)Stokes–Onsager–Stefan–Maxwell system, which governs molecular diffusion and convection within a non-ideal, single-phase fluid composed of multiple species, in the regime of low Reynolds number in the steady state. We propose an appropriate Picard linearisation posed in a novel Sobolev space relating to the diffusional driving forces, and prove convergence of a structure-preserving finite element discretisation. The broad applicability of our theory is illustrated with simulations of the centrifugal separation of noble gases and the microfluidic mixing of hydrocarbons.