Since 2002 Perimeter Institute has been recording seminars, conference talks, public outreach events such as talks from top scientists using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities.
Recordings of events in these areas are all available and On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA). PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
Accessibly by anyone with internet, Perimeter aims to share the power and wonder of science with this free library.
The based loop group is an inﬁnite-dimensional manifold equipped with a Hamiltonian action of a ﬁnite dimensional torus. This was studied by Atiyah and Pressley. We investigate the Duistermaat–Heckman distribution using the theory of hyperfunctions. In applications involving Hamiltonian actions on inﬁnite-dimensional manifolds, this theory is necessary to accommodate the existence of the inﬁnite order diﬀerential operators which aries from the isotropy representation on the tangent spaces to ﬁxed points. (Joint work with James Mracek)
This is a joint work with T. Pantev. In this talk, we will discuss moduli of ﬂat bundles on smooth algebraic varieties, with possibly irregular singularities at inﬁnity. For this, we use the notion of “formal boundary”, previously studied by Ben Bassat-Temkin, Eﬁmov and Hennion– Porta–Vezzosi, as well as the moduli of ﬂat bundles at inﬁnity. We prove that the ﬁbers of the restriction map to inﬁnity are representable. We also prove that this restriction map has a canonical Lagrangian structure in the sense of shifted symplectic geometry.
It is conventional wisdom among physicists that anomalies of fermionic theories measure an obstruction to the existence of a well-defined (gauge-invariant) partition function. The aim of this talk is to use the formalism of Costello and Gwilliam to show how this wisdom is instantiated for perturbative anomalies of the massless free fermion. We will show how an action of a dg Lie algebra L on the massless free fermion theory gives rise to a line bundle over the formal moduli problem corresponding to L; the anomaly is precisely the failure of this line bundle to be trivial.
The generalized double semion model, introduced by Freedman and Hastings, is a lattice field theory similar to the toric code, with a gapped Hamiltonian whose space of ground states depends on the topology of the ambient manifold. In this talk, I’ll explain how to calculate its low-energy limit, which forms part of a topological field theory, in terms of characteristic classes of the ambient manifold.
I’ll discuss some results and expectations about the behavior of branes in Betti geometric Langlands under cutting and gluing Riemann surfaces.
The goal of my talk will be to discuss the relation between two approaches to the geometric Langlands program. The ﬁrst has been proposed by Beilinson and Drinfeld, using ideas and methods from conformal ﬁeld theory (CFT). The second was initiated by Kapustin and Witten based on a topological version of four-dimensional maximally supersymmetric Yang–Mills theory and its reduction to a two-dimensional topological sigma model.
I will describe examples of holomorphic N=1 super-symmetric vertex algebras with small (non-zero) values of the elliptic genus. I will speculate on a relation to certain patterns in the theory of topological modular forms.
Check back for details on the next lecture in Perimeter's Public Lectures Series