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Calendar of Physics Talks Vienna
| Where Time Begins: Causal Consequences of Signature Change |
| Speaker: | Nathalie RIEGER (Yale University) |
| Abstract: | The Hartle-Hawking "no-boundary" proposal redefines spacetime by offering a new way of thinking about the origin of the universe. Mathematically, this involves signature-type changing manifolds where a Riemannian region is smoothly joined to a Lorentzian region at the transition surface where time begins.
Motivated by the "no-boundary" proposal, I present a segment of a new framework for signature-changing manifolds, characterized by a degenerate yet smooth metric. Then I adapt some Lorentzian tools and results to the signature-type changing scenario, introducing new definitions that carry unforeseen causal implications. One such noteworthy consequence is the presence of time-reversing loops through each point on the locus of signature change. |
| Date: | Tue, 17.06.2025 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger Lecture Hall, 1090 Vienna, Boltzmanngasse 5, 5th floor |
| Contact: | S. Fredenhagen, M. Sperling |
| Inclusive semileptonic B decays: Current status and perspectives |
| Speaker: | Thomas MANNEL (University of Siegen) |
| Abstract: | Inclusive decays of hadrons with a single heavy quark can be described using the Heavy Quark Expansion (HQE).
After a brief introduction and motivation I will discuss the current status of the calculations used to extract the CKM matrix element Vcb and will give the perspectives to further increase the precision of the HQE. |
| Date: | Tue, 17.06.2025 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger Lecture Hall, 1090 Vienna, Boltzmanngasse 5, 5th floor |
| Contact: | A. Hoang, H. Neufeld, J. Pradler, M. Procura |
| Time-periodic solutions to the 1D cubic wave equation |
| Speaker: | Filip FICEK (University of Vienna) |
| Abstract: | Time-periodic solutions to nonlinear dispersive equations have been the subject of many investigations over the years. The classic works prove the existence of small amplitude solutions with frequencies belonging to nowhere dense sets.
In this talk I will show numerical evidence suggesting existence of a completely new class of solutions for one-dimensional cubic wave equation on an interval with Dirichlet boundary conditions. Solutions belonging to it are characterised by large energies, have complicated mode compositions, and form intricate fractal-like patterns. Then I will show how these numerical results can be used to rigorously construct exact solutions belonging to this new class. Finally, I will demonstrate a systematic approach to analysing complex structures formed by these solutions. |
| Date: | Wed, 18.06.2025 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Seminarraum A, Waehringer StraÃe 17, 1090 Vienna, 2nd floor |
| Contact: | D. Fajman |
| Towards strong coupling of polar molecules to a superconducting resonator |
| Speaker: | Nikolaus De Zordo (TU Wien Atominstitut) |
| Abstract: | Hybrid quantum systems are a well-established tool in quantum science and technology. Building up on our latest results, where we successfully strongly coupled sodium atoms embedded in a noble gas neon matrix to the magnetic field of our resonator, we present a novel concept which aims to couple superconducting resonators to cryogenic crystals (solid hydrogen, Ne, Ar,...) doped with polar molecules (ND3,. . . ). By implanting molecules in such noble gas crystals, they can be kept very close to the resonators surface where electric coupling is maximized. Deuterated ammonia has an electric dipole moment of 1.5 Debye and an inversion transition of 1.6 GHz which will be the transition coupled to the microwave resonator. By its nature, the electric fieldâs coupling strength is orders of magnitude greater than the magnetic coupling strength, which will allow us to enter the strong
coupling reg |
| Date: | Wed, 18.06.2025 |
| Time: | 16:15 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Maximilian Prüfer |
| Precision in bound muon physics with EFT techniques |
| Speaker: | Duarte FONTES (KIT) |
| Abstract: | Muon conversion â the process of a bound muon decaying into an energetic electron â provides one of the most stringent limits on Charged Lepton Flavor Violation. The experimental limit is soon expected to improve by four orders of magnitude, thus calling for precise theoretical predictions. The latter are usually described with perturbation theory using an Effective Field Theory (EFT) valid at the nuclear mass. However, muon conversion involves a multiplicity of scales below the nuclear mass, which spoil the convergence of perturbation theory.
In this talk, I present a framework to overcome this problem, by resorting to a series EFTs. Combining Heavy Quark Effective Theory (HQET), Non-Relativistic QED (NRQED), potential NRQED, Soft-Collinear Effective Theory I and II and boosted HQET, I derive a factorization theorem and present the renormalization group equations. |
| Date: | Fri, 20.06.2025 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger Lecture Hall, 1090 Vienna, Boltzmanngasse 5, 5th floor |
| Contact: | A. Hoang, J. Pradler, M. Procura |
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