Oberseminar Differentialgeometrie: Stefan Schreieder (Universität Hannover), Vortrag: Holomorphic one-forms without zeros
Monday, 08.04.2024 16:00 im Raum SRZ 214
Abstract: We discuss a conjecture of Kotschick which predicts that a compact Kähler manifold admits a holomorphic one-form without zeros if and only if the underlying real manifold admits a smooth fibration over the circle. In particular, we will explain that this conjecture holds for smooth projective threefolds (joint work with Feng Hao) and that it is closely related to a Conjecture of Bobadilla?Kollár which predicts that a proper map between complex manifolds is submersive if and only if it is a homological fibre bundle (joint with Ruijie Yang).
Angelegt am Thursday, 07.03.2024 08:29 von Sandra Huppert
Geändert am Thursday, 07.03.2024 08:29 von Sandra Huppert
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Sarah-Jean Meyer, Univ. Oxford: The FBSDE approach to sine-Gordon up to 6π (Oberseminar Mathematische Stochastik)
Wednesday, 10.04.2024 16:00 im Raum SRZ 204
I will present a stochastic analysis of the sine-Gordon Euclidean quantum field (cos(β φ))_2 on the full space up to the second threshold, i.e. for β^2<6*π. The basis of our method is a stochastic quantisation equation given by a forward-backward stochastic differential equation (FBSDE) for a decomposition (X_t)_(t≥0) of the interacting Euclidean field X_∞ along a scale parameter t≥0 using an approximate version of the renormalisation flow equation. The FBSDE produces a scale-by-scale coupling of the interacting field with the Gaussian free field without cut-offs and describes the optimiser of a stochastic control problem for Euclidean QFTs introduced by Barashkov and Gubinelli. I will first explain the general set-up for the FBSDE approach. In the case of the sine-Gordon model, I will showcase some applications of the FBSDE to illustrate that it can be used effectively to obtain results about large deviations, integrability, decay of correlations for local observables, singularity with respect to the free field, Osterwalder-Schrader axioms and other properties. This is joint work with Massimiliano Gubinelli.
Angelegt am Monday, 29.01.2024 15:44 von Anita Kollwitz
Geändert am Friday, 22.03.2024 10:31 von Claudia Lückert
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Wilhelm Killing Kolloquium: Prof. Dr. Antti Knowles (University of Geneva): Random graphs as models of quantum disorder
Thursday, 11.04.2024 14:15 im Raum M4
A disordered quantum system is mathematically described by a large Hermitian random matrix. One of the most remarkable phenomena expected to occur in such systems is a localization-delocalization transition for the eigenvectors. Originally proposed in the 1950s to model conduction in semiconductors with random impurities, this phenomenon is now recognized as a general feature of wave transport in disordered media, and is one of the most influential ideas in modern condensed matter physics. A simple and natural model of a disordered quantum system is given by the adjacency matrix of a random graph. I report on recent progress in analysing the phase diagram for the Erdös-Renyi model of random graphs. In particular, I explain the emergence of fully localized and fully delocalized phases, which are separated by a mobility edge. Joint work with Johannes Alt and Raphael Ducatez.
Angelegt am Wednesday, 07.02.2024 10:57 von Claudia Lückert
Geändert am Tuesday, 05.03.2024 15:28 von Claudia Lückert
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Christiane Klein (Université Grenoble-Alpes): Quantum effects on the strong cosmic censorship conjecture
Tuesday, 16.04.2024 12:00 im Raum 503
The strong cosmic censorship conjecture states that the inner horizons of
black holes should become singular to avoid travel into spacetime regions where
determinism breaks down. In this talk, I present results on the influence of
quantum effects on the strong cosmic censorship conjecture in asymptotically de Sitter black
hole spacetimes. I will discuss the universality of these effects and present numerical
results also showing how the quantum effects may influence the charge and angular
momentum of the black hole.
Angelegt am Thursday, 28.03.2024 07:10 von Anke Pietsch
Geändert am Thursday, 28.03.2024 07:10 von Anke Pietsch
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Christiane Klein (Université Grenoble-Alpes): Quantum effects on the strong cosmic censorship conjecture
Tuesday, 16.04.2024 12:00 im Raum 503
The strong cosmic censorship conjecture states that the inner horizons of
black holes should become singular to avoid travel into spacetime regions where
determinism breaks down. In this talk, I present results on the influence of
quantum effects on the strong cosmic censorship conjecture in asymptotically de Sitter black
hole spacetimes. I will discuss the universality of these effects and present numerical
results also showing how the quantum effects may influence the charge and angular
momentum of the black hole.
Angelegt am Tuesday, 26.03.2024 11:24 von Anke Pietsch
Geändert am Tuesday, 26.03.2024 11:24 von Anke Pietsch
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