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Calendar of Physics Talks Vienna
| Compositional quantum field theory: An axiomatic framework and its applications |
| Speaker: | Robert Oeckl (University of Vienna) |
| Abstract: | We review aspects of the axiomatic program of compositional quantum field theory from its origins in TQFT to its aspirations in quantum gravity. We present some of its applications so far: From a generalized S-matrix via evanescent particles to the time-of-arrival problem. We point out open problems and some future directions. |
| Date: | Tue, 25.03.2025 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-HS, Boltzmanngasse 5, 1090 Wien, 5.Stock |
| Contact: | S. Fredenhagen, M. Sperling |
| Nonlinear Relativistic Structure Formation in ÎCDM |
| Speaker: | Marco Bruni (University of Portsmouth) |
| Abstract: | In this talk I will give an overview of work on nonlinear structure formation in the the standard model of cosmology, ÎCDM, assuming General Relativity (GR).
Starting from briefly presenting a post-Friedmann approximation (similar to post-Minkowski, but on a cosmological background and assuming small peculiar velocities), I will show how at leading order the gravito-magnetic effect (AKA frame-dragging) can be extracted from standard Newtonian N-body simulations, as well as from N-body simulations with GRAMSES, an approximate GR code. I will then present full-GR simulations of a toy-model âcosmic webâ of over-densities, voids and filaments with the Einstein Toolkit fluid code, showing how the first shell-crossing at peaks of over-densities is very well predicted by the simple "top hat" model, while in the formation of the cosmic web a role is played by gravito-magnetism, especiall |
| Date: | Wed, 26.03.2025 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Seminar Room A, Waehringer Str. 17, 1090 Wien, 2nd floor |
| Contact: | D. Fajman |
| The 3D printer as a reactor for new material chemistry: Opportunities for multi-material fabrication |
| Speaker: | Katharina Ehrmann (Institute of Applied Synthetic Chemistry, TU Wien) |
| Abstract: | True multi-material printing from one resin has recently become one of the focus areas in the light-based 3D printing community. Specifically, the use of varying irradiation intensities (greyscale lithography) or different colours of light (multi-wavelength printing) have been demonstrated as powerful printing parameters, with which stiff and soft parts can be printed within one resin.
This talk will explore the advancement of greyscale lithography beyond the current scope.
The promise of multi-wavelength 3D printing based on wavelength-orthogonal reactions will be discussed by introducing a first proof of principle for fully orthogonal 3D printing via two colours of light to create degradable vs. non-degradable objects. |
| Date: | Wed, 26.03.2025 |
| Time: | 15:15 |
| Duration: | 45 min |
| Location: | Freihaus, Seminarraum DC rot 07 (roter Bereich, 7. OG) |
| Contact: | Evan Constable |
| Expansion by Regions for Feynman integrals: From Wide-angle to Spacelike Collinear Kinematics |
| Speaker: | Yao MA (ETH Zurich) |
| Abstract: | The expansion by regions is a powerful technique for analyzing the asymptotic behavior of Feynman integrals, where the first critical step is identifying all relevant regions. In Euclidean kinematics, this can be systematically formulated as an "expansion by subgraphs" procedure. However, in Minkowski kinematics, region identification becomes nontrivial due to infrared singularities and non-Euclidean causal structure.
In this talk, we explore asymptotic expansions for massless scattering processes across both wide-angle and small-angle kinematics. We review recent progress in region identification and show how the expansion-by-subgraphs technique extends to these scenarios. A key result is that a "spacelike collinearization" procedureâtransitioning systematically from wide-angle to collinear kinematicsâreveals Glauber modes as emergent from the Landshoff scattering picture. |
| Date: | Fri, 28.03.2025 |
| Time: | 14:00 |
| Location: | Seminar room 3158, 1st floor Boltzmanngasse Zubau, Boltzmanngasse 5, 1090 Wien |
| Contact: | A. Hoang, M. Procura |
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