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Calendar of Physics Talks Vienna
| Generalised symmetries from five-brane webs |
| Speaker: | Federico Carta (INFN, Bologna) |
| Abstract: | Five-dimensional superconformal field theories are often intrinsically strongly coupled and lack a conventional Lagrangian description. String theory nevertheless provides concrete constructions of these theories through M-theory on singular Calabi–Yau threefolds and Type IIB (p,q)-five-brane webs.
The first part of this talk will be an introduction to five-brane webs and generalised global symmetries. I will then explain how one-form symmetries can be determined directly from the brane picture. Line operators are represented by D3-branes and attached strings, while screening by local operators is realised through string junctions, Higgsing and Hanany–Witten transitions. For ordinary brane webs, this microscopic picture reproduces the results previously obtained in the literature. I will finally discuss how the analysis is extended in the presence of orientifold O7 and O5 planes. |
| Date: | Tue, 06.10.2026 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | ESI - Boltzmann lecture hall, Boltzmanngasse 9, 1090 Wien |
| Contact: | S. Fredenhagen, M. Sperling |
| Towards a Theory of Dissipative Dark Matter |
| Speaker: | Garance Lankester-Broche (University of Vienna) |
| Abstract: | On small cosmological scales, self-interacting dark matter can modify the thermodynamics of dark matter (DM) halos through heat transport. Dissipative channels beyond elastic DM self-scattering enable cooling, leading to additional modifications in the evolution of the galactic DM halos. In this talk, a set of representative dissipative scenarios is investigated to understand how the microscopic properties of the DM candidates shape the resulting cooling. I will present a description of these dissipative processes both, from the perspective of perturbative QFT as well from a treatment that is exact in the interaction of the scattering DM particles. The latter treatment provides a unified description of radiative processes across all relevant kinematic regimes, continuously connecting the perturbative Born limit into the classical regime. |
| Date: | Tue, 06.10.2026 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-HS, Boltzmanngasse 5, 1090 Wien, 5.Stock |
| Contact: | A. Hoang, M. Procura, J. Pradler |
| Life on an Endless Hill: Making Sense of Up-Side-Down Potentials in Quantum Mechanics and High Energy Physics |
| Speaker: | Paul Romatschke (TU Wien) |
| Abstract: | In classical physics, unbounded (or "up-side-down") potentials do not allow for a stable ground state. As a consequence, unbounded potentials have often been dismissed as not viable for proper unitary quantum theories. Historically, we have learned that the quantum world often contradicts dearly held beliefs based on classical physics. By contrast, mathematics has been recognized as a good guide even when classical intuition fails. In this talk, I will use well-developed mathematics to explore physical systems with up-side-down and non-Hermitian potentials in quantum mechanics and quantum field theory, with applications to AMO experiments, high energy physics and Quantum Chromodynamics. |
| Date: | Wed, 07.10.2026 |
| Time: | 11:00 |
| Duration: | 60 min |
| Location: | Besprechungsraum 2 (Marietta Blau Institute for Particle Physics, Dominikanerbastei 16 [PSK], 1010 Vienna) |
| Contact: | Josef.Pradler@josef.pradler@univie.ac.at |
| The Critical Collapse of a Perfect Fluid in Infinite Dimensions |
| Speaker: | Craig Clark (SNS/INFN Pisa) |
| Abstract: | I will review a series of impressive numerical calculations from the 90s that revealed universal scaling behaviour in gravitational collapse. I will then focus on spherically symmetric perfect fluid collapse and explain how treating the number of spacetime dimensions, D, as an expansion parameter gives us analytic control of its continuously self-similar critical solution. In a 1/D expansion, we construct this solution and compute its critical exponent. At leading order, the length-scaling exponent is 1/2 and does not depend on the fluid’s equation of state parameter, a simplification reminiscent of mean-field behaviour. This rich system provides many potential routes for exploring universality in classical gravity. Based on a series of forthcoming papers with Guilherme L. Pimentel. |
| Date: | Thu, 08.10.2026 |
| Time: | 16:00 |
| Location: | ITP, TU Wien, Wiedner Hauptstr. 8-10, Sem.R. DB gelb 10 |
| Contact: | Daniel Grumiller, Gerben Oling |
| Quantum Correlations and Relativistic Effects in Optical Atomic Clocks |
| Speaker: | Klemens Hammerer (UIBK) |
| Abstract: | Optical atomic clocks are the most precise measurement devices available today, reaching accuracies that correspond to a drift of less than one second over the age of the universe and enabling applications ranging from improved timekeeping and navigation to tests of fundamental physics at the interface of quantum theory and relativity. In this colloquium, I will first discuss the challenge of exploiting quantum correlations between atoms to further improve clock stability, emphasizing that their benefit depends on how well they are adapted to the dominant noise sources and experimental constraints. I will then turn to relativistic effects in optical atomic clocks, which at current levels of precision become directly relevant: they must be accounted for as systematic shifts, but also provide opportunities for sensing gravitational and kinematic effects. In particular, I will outline how n |
| Date: | Fri, 09.10.2026 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal, ATI |
| Contact: | Uros Delic |
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