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Calendar of Physics Talks Vienna
| Massive Higher-Spin Fields in Three-Dimensional Asymptotically Flat Spacetimes |
| Speaker: | Michel Pannier (University of Jena) |
| Abstract: | Three-dimensional gravity is often employed as a toy model for applications in the context of the Holographic Principle. The purely topological nature of this theory, however, may render it too simple to reveal insights into the working mechanisms of Holography and, thus, one may introduce extra degrees of freedom, for example via the coupling to a scalar or higher-spin field. In this talk I will present a simple way to describe the propagation of massive scalar and higher-spin fields on a fixed asymptotically flat spacetime in 3D, thereby providing a mechanism that effectively unfolds the equations of Fierz and Pauli. I will also discuss a suitable higher-spin generalisation of flat-space boundary conditions. |
| Date: | Tue, 25.10.2022 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-Hoersaal, University of Vienna, Boltzmanngasse 5, 5th floor, Room Nr. 3500 |
| Contact: | S. Fredenhagen, D. Grumiller, E. Battista, R. Ruzziconi |
| The azimuthal decorrelation in V+jet production and the Winner-Takes-All axis |
| Speaker: | Rudi Rahn (University Amsterdam / Nikhef) |
| Abstract: | The azimuthal decorrelation between a vector boson and a jet is an essential hard probe in high energy proton-proton and heavy-ion collisions.It suffers from large logarithms in the back-to-back limit, which can be resummed using Soft-Collinear Effective Theory.In this talk I will demonstrate that a suitable choice of jet recombination,the Winner-Takes-All recombination scheme, simplifies the observable tremendously and allows us to derive resummed predictions at next-to-next-to-leading logarithmic accuracy,while maintaining a rich selection of interesting features.We find for example that linearly polarised collinear functions must be included,and that the observable can be measured with minimal impact on particle tracks.Finally I will contrast the azimuthal decorrelation with a closely related observable the radial decorrelation,to motivate why the former is so theoretically accessible |
| Date: | Tue, 25.10.2022 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-Hoersaal, Fakultaet für Physik, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, M. Procura, A. Broggio |
| The Riemannian Penrose inequality for asymptotically flat half-spaces and rigidity |
| Speaker: | Thomas Koerber (Vienna) |
| Abstract: | Asymptotically flat half-spaces (M,g) are asymptotically flat manifolds with a non-compact boundary. They naturally arise as suitable subsets of initial data for the Einstein Field equations.In this talk I will present a proof of the Riemannian Penrose inequality for asymptotically flat half-spaces with horizon boundary (joint with M. Eichmair) that works in all dimensions up to seven.This inequality gives a sharp bound for the area of the horizon boundary in terms of the half-space mass of (M,g). To prove the inequality, we double (M, g) along its non-compact boundary and smooth the doubled manifold appropriately. To prove rigidity,we use variational methods to show that,if equality holds,the non-compact boundary of (M,g) must be totally geodesic.I will also explain how our techniques can be used to prove rigidity for the Riemannian Penrose inequality for asymptotically flat manifolds. |
| Date: | Thu, 27.10.2022 |
| Time: | 15:15 |
| Duration: | 60 min |
| Location: | Seminarraum A, Währinger Strasse 17, 2. Stock |
| Contact: | P. Chrusciel, D. Fajman |
| Compressibility and the equation of state of an optical quantum gas in a box |
| Speaker: | Julian Schmitt (University of Bonn) |
| Abstract: | Quantum gases of atoms, exciton-polaritons, and photons provide a test bed for many-body physics under both in- and out-of-equilibrium settings. Experimental control over their dimensionality, potential energy landscapes, or the coupling to reservoirs offers wide possibilities to explore phases of matter, for example, by probing susceptibilities, as the compressibility. For gases of material particles, such studies of the mechanical response are well established, in fields from classical thermodynamics to cold atomic quantum gases; for optical quantum gases, they have so far remained elusive.
In my talk, I will discuss experimental work demonstrating a measurement of the compressibility of a two-dimensional quantum gas of photons in a box potential, from which we obtain the equation of state for the optical medium. The experiment is carried out in a nanostructured dye-filled optical micr |
| Date: | Fri, 28.10.2022 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | ATI Hörsaal/https://tuwien.zoom.us/j/93672218922?pwd=dEZNQ2liVzRNNURvNmVWVE5KUWRiQT09 |
| Contact: | Maximilian Prüfer |
| Loops, birdtracks and 6js -- exploring QCD color structure |
| Speaker: | Judith Alcock-Zeilinger (ESI) |
| Abstract: | This talk aims to motivate how the birdtrack formalism -- a
powerful graphical framework in which one can perform group theoretic
calculations -- can be used to analyze and better understand QCD color
structures: First, I will motivate how to decompose complicated color
structures into simpler tree-level diagrams and so-called Wigner-6j
symbols. We will then explore a particular class of 6j symbols, namely
those containing two quark lines, and discover a closed form
expression of these 6js through the use of the birdtrack formalism.
The results presented in this talk are based on recent work of S.
Keppeler, S. Plätzer, M. Sjödahl and myself (arXiv:2209.15013). |
| Date: | Fri, 28.10.2022 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-Hoersaal, Fakultaet für Physik, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, M. Procura, S. Plaetzer |
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