Talks in mathematical physics

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Autumn Semester 2016

Date / Time

Speaker

Title

Location

* 29 September 2016
11:15-12:15

Francis Brown
Oxford

Event Details

Talks in Mathematical Physics

Title	Grothendieck-Teichmüller theory in genus 1
Speaker, Affiliation	Francis Brown, Oxford
Date, Time	29 September 2016, 11:15-12:15
Location	CLV B 4

Grothendieck-Teichmüller theory in genus 1

CLV B 4

3 November 2016
15:15-16:15

Boris Pioline
CERN

Event Details

Talks in Mathematical Physics

Title	Indefinite theta series and generalized error functions
Speaker, Affiliation	Boris Pioline, CERN
Date, Time	3 November 2016, 15:15-16:15
Location	HG G 43

Indefinite theta series and generalized error functions

HG G 43

10 November 2016
15:15-16:15

Vera Vértesi
Université de Strasbourg

Event Details

Talks in Mathematical Physics

Title	Combinatorial tangle Floer homology
Speaker, Affiliation	Vera Vértesi, Université de Strasbourg
Date, Time	10 November 2016, 15:15-16:15
Location	HG G 43
Abstract	Knot Floer homology is an invariant for knots and links defined by Ozsvath and Szabo and independently by Rasmussen. It has proven to be a powerful invariant e.g. in computing the genus of a knot, or determining whether a knot is fibered. In this talk I define a generalisation of knot Floer homology for tangles; Tangle Floer homology is an invariant of tangles in D³, S²xI or in S³. Tangle Floer homology satisfies a gluing theorem and its version in S³ gives back a stabilisation of knot Floer homology. Finally, I will discuss how to see tangle Floer homology as a categorification of the Reshetikhin-Turaev invariant.

Combinatorial tangle Floer homologyread_more

HG G 43

* 23 November 2016
16:15-17:15

Prof. Dr. Gabriele Nebe
RWTH Aachen

Event Details

Talks in Mathematical Physics

Title	Automorphisms of Extremal Lattices
Speaker, Affiliation	Prof. Dr. Gabriele Nebe, RWTH Aachen
Date, Time	23 November 2016, 16:15-17:15
Location	HG G 19.1

Automorphisms of Extremal Lattices

HG G 19.1

1 December 2016
15:15-16:15

David Hernandez
Université de Paris

Event Details

Talks in Mathematical Physics

Title	Spectra of quantum KdV Hamiltonians, Langlands duality and category O for quantum affine algebras
Speaker, Affiliation	David Hernandez, Université de Paris
Date, Time	1 December 2016, 15:15-16:15
Location	HG G 43

Spectra of quantum KdV Hamiltonians, Langlands duality and category O for quantum affine algebras

HG G 43

8 December 2016
15:15-16:15

Igor Khavkine
Università di Roma

Event Details

Talks in Mathematical Physics

Title	Spectral theory of vector and tensor fields on Schwarzschild spacetime
Speaker, Affiliation	Igor Khavkine, Università di Roma
Date, Time	8 December 2016, 15:15-16:15
Location	HG G 43
Abstract	After a separation of variables ansatz, the equations for vector and tensor test fields on a Schwarzschild black hole background reduce to radial ODEs. More precisely, we refer to the wave equation for vector fields and the Lichnerowicz equation for metric perturbations. These equations can be thought of as the harmonic gauge versions of, respectively, the Maxwell and linearized Einstein equations. These radial ODEs pose a spectral problem that is non-standard in several ways: they are coupled matrix equations, they are not naturally self-adjoint on a function space with a positive definite inner product, and the spectral parameter appears non-linearly (both linearly and quadratically). Nevertheless, we can realize these differential equations as closed operators between certain Hilbert spaces, with purely real spectrum (in the sense of operator pencils). This result is only possible due to an explicit and highly non-trivial equivalence of these equations to systems of decoupled generalized Regge-Wheeler scalar equations, which are known to pose standard self-adjoint spectral problems.

Spectral theory of vector and tensor fields on Schwarzschild spacetimeread_more

HG G 43

15 December 2016
15:15-16:15

Christoph Keller
ETH Zurich

Event Details

Talks in Mathematical Physics

Title	Mathieu Moonshine and Symmetry Surfing
Speaker, Affiliation	Christoph Keller, ETH Zurich
Date, Time	15 December 2016, 15:15-16:15
Location	HG G 43
Abstract	I will give a brief introduction to moonshine, the surprising connection between modular forms and sporadic simple groups. I will quickly discuss the original monstrous moonshine, and then talk about the more recently discovered Mathieu moonshine. I will explain why the explanation of the original moonshine most likely does not work for this new type of moonshine. I will then discuss a proposed explanation due to Taormina and Wendland, namely the idea of `symmetry surfing', i.e. combining the symmetries of different K3 sigma models. I will present some new results which provide evidence that symmetry surfing should work also for all higher BPS states. This is based on work with Matthias Gaberdiel and Hynek Paul.

Mathieu Moonshine and Symmetry Surfingread_more

HG G 43

16 December 2016
13:00-14:00

Pavel Mnev
University of Notre Dame

Event Details

Talks in Mathematical Physics

Title	Towards derived Wilson's RG flow along the poset of CW complexes: case of cellular non-abelian BF theory
Speaker, Affiliation	Pavel Mnev, University of Notre Dame
Date, Time	16 December 2016, 13:00-14:00
Location	Y27 G 28
Abstract	Simple homotopy equivalence of CW complexes is generated by local moves - Whitehead’s elementary expansions and collapses of CW complexes. To a collapse Y —> X, one can associate an elementary (i,p,K)-triple (chain contraction data) from the cochains of the larger complex Y to cochains of the smaller complex X. This triple defines the gauge-fixing data for an elementary BV pushforward from the cellular BF theory on Y onto X. This pushforward disagrees with the “standard” cellular BF theory on X by a homotopy of solutions of the quantum master equation (a canonical transformation). If X is a cellular aggregation of Y (i.e. Y is a subdivision of X), one can present the move Y —> X as a particular sequence of expansions and collapses. To each such presentation, there corresponds a particular distinguished (i,p,K) triple preserving integral cochains. The program is to encode the “disagreement” above in a systematic way in the “derived” (or “Q-exact”) Wilson’s RG flow (for cellular BF theory) along the poset of CW complexes. A related concept is the Q-exact stress-energy tensor in cellular BF theory. The program is substantiated by an explicit computation, corresponding to the star aggregation for the BF theory on a 2-simplex.

Towards derived Wilson's RG flow along the poset of CW complexes: case of cellular non-abelian BF theoryread_more

Y27 G 28

* 17 January 2017
14:00-15:00

Marko Zivkovic
University of Luxembourg

Event Details

Talks in Mathematical Physics

Title	Multi-oriented graph complexes
Speaker, Affiliation	Marko Zivkovic, University of Luxembourg
Date, Time	17 January 2017, 14:00-15:00
Location	HG G 19.1
Abstract	We introduce the sequence of multi-oriented graph complexes, the 0-oriented one being the standard Kontsevich's graph complex. We provide direct combinatorial quasi-isomorphisms between them, showing that the homologies of all such graph complexes are indeed the same.

Multi-oriented graph complexesread_more

HG G 19.1

Note: events marked with an asterisk (*) indicate that the time and/or location are different from the usual time and/or location.

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