Geometry and Quantum Theory (GQT)


The GQT colloquium takes place on the final two days, Nov 29 and 30, and consists of nine research talks. These are attended by Ph.D. students, members of the GQT staff, and visitors from abroad. We aim at organizing research talks which feature topics covered during the school, though some of the talks are unrelated.

The program is as follows:

Thursday 29 Nov

9:00-10:00: arrival
10:00-11:00: Bohmann
11:30 -12:30: Heuts
14:00-15:00: Tam
15:30-16:30: Hausmann
18:30: dinner

Friday 30 Nov
9:00-10:00: Sibilla
10:15 – 11:15: Goncalves de Martino  
11:30 – 12:30: Nadimpalli
14:00-15:00: Sauvaget
15:30 – 16:30: Wong



Anne Marie Bohmann (Vanderbilt)

Loop spaces,  coTHH, and a new spectral sequence

Given a space with its diagonal map,  we construct a topological invariant called “topological coHochschild homology.” This is in fact a special case of an invariant for a coalgebral. It generalizes a classical algebraic invariant of coalgebras due to Doi.  We show  this invariant is related to algebraic K- theory and Waldhausen’s A-theory. In the case of a space with the diagonal map, we obtain the free loop space, which indicates connections to string topology as well.    Additionally, we build a new spectral sequence to calculate topological coHochschild homology, which allows for new computational techniques. This it’s joint work with Gerhardt, Hogenhaven, Shipley and Ziegenhagen.

Markus Hausmann (Copenhagen)

Commuting Matrices and Atiyah’s Real K-theory

Let G be a Lie group and n a natural number. The space C_n(G) of n commuting elements of G is a classical object of study, with connections to mathematical physics and interesting homotopy-theoretic properties. This talk will concern the spaces of commuting elements in the stable unitary group U and the stable orthogonal group O. I will explain how the homotopy groups of C_n(U) can be computed via stable homotopy theory and those of C_n(O) via equivariant stable homotopy theory, the main tool being Atiyah’s Real K-theory spectrum. This is joint work with Simon Gritschacher.

Marcelo Goncalves de Martino (Oxford)

On the Dunkl version of a Howe duality

In this talk, I will report on a joint work (in progress) with D. Ciubotaru, in which we investigate the Dunkl version of the classical Howe duality (O(r),spo(2|2)). Similar deformed versions of Howe dualities, specially in the (Pin(r),spo(2|1))-case, were discussed before in, for example, the works of Ben-Said, De Bie, Oste, Orsted, Soucek, Somberg and Van der Jeugt. Our work builds on the notion of a Dirac operator for Drinfeld algebras recently introduced by Ciubotaru, which was inspired by the analogous theory for Lie algebras (and the work of Vogan, Huang and Pandzic), as well as the work of Cheng and Wang on classical Howe dualities.

Adrien Sauvaget (Utrecht)

Mazur-Veech volumes and intersection theory in the Hodge Bundle

In the 80’s Mazur and Veech defined a volume form on moduli spaces Riemann surfaces endowed with a differential form with prescribed singularities. This volume form is a powerful tool to compute dynamical invariants of these surfaces. We will discuss the problem of expressing this volume form as product of Chern forms of “tautological” line bundles.