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Calendar of Physics Talks Vienna
| “α_s from non-strange hadronic tau decays“ |
| Speaker: | Santiago Peris (IFAE, Barcelona) |
| Date: | Tue, 06.03.2018 |
| Time: | 16:15 |
| Location: | Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | G. Ecker, H. Neufeld |
| Low regularity Lorentzian metrics and the causal character of maximizers |
| Speaker: | Melanie Graf (Vienna) |
| Abstract: | For metrics that are at least C1,1 maximizing curves must be solutions of the geodesic equation and hence cannot change causal character: they must remain either timelike or null. This is no longer obvious for metrics of lower regularity and once the regularity drops below Lipschitz there are examples of "bubbling" metrics, for which maximizing causal curves may contain both timelike and null segments. We will present a recent result stating that Lipschitz regularity of the metric is sufficient for maximizing curves to have fixed causal character
and show how this almost immediately gives a Lipschitz inextendibility result for timelike geodesically complete spacteimes. This is joint work with E. Ling.
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| Date: | Thu, 08.03.2018 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel |
| BLACK HOLE DEGENERACIES & GOPAKUMAR-VAFA INVARIANTS FROM MATHIEU MOONSHINE |
| Speaker: | Aradhita Chattopadhyaya (Indian Institute of Science) |
| Abstract: | The talk is based to 2 papers and is divided into two parts based on the papers: arxiv 1704.00434 & arxiv 1712.08791 respectively.
Part-I:
We study Siegel modular forms associated with the theta lift of twisted elliptic genera of K3 orbifolded with g' corresponding to the conjugacy classes of the Mathieu group M_{24}. We show that the Siegel modular forms satisfy the required properties for them to be generating functions of 1/4 BPS dyons of type II string theories compactified on K3xT^2 and orbifolded by g'.
Part-II:
We evaluate the low energy gravitational couplings, F_g in the heterotic E_8xE_8 string theory compactified on orbifolds of K3xT^2 by g'. The holomorphic piece of F_g is given in terms of a polylogarithim with index 3-2g and predicts the Gopakumar-Vafa
invariants in the corresponding dual type II Calabi-Yau compactifications. |
| Date: | Thu, 08.03.2018 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna) |
| Contact: | Timm Wrase |
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