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Calendar of Physics Talks Vienna
| String modes and fuzzy field theories in string modes formalism |
| Speaker: | Jurai Tekel (Comenius University Bratislava, Slowakia) |
| Abstract: | Fuzzy spaces are,among other things,toy models for spaces with a discrete structure at small distances.As such,they provide a laboratory to study the consequences of this discreteness on the properties of
physical theories,for example,the theory of scalar fields.The standard approach to this theory is very similar to the usual treatment of field theories on continuous spaces - momentum basis,Feynman diagrams,and loop integrals.In this talk we present a different formulation of the scalar field theory on the fuzzy sphere - in terms of the string modes,which are functions optimally localized in position and momentum space.We will first introduce the string modes and highlight their most important properties.Then we will show how they greatly simplify the computation of loop contributions in scalar field theory in position space and lead to some new insights into the structure of the action |
| Date: | Tue, 22.03.2022 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Erwin-Schrödinger-Hörsaal, University of Vienna, Boltzmanngasse 5, 5th floor, Room Nr. 3500 |
| Contact: | S. Fredenhagen, D. Grumiller, E. Battista, R. Ruzziconi |
| Visualizing Nanoscale Surface Chemistry: From Ultra-High Vacuum to Electrochemical Environments |
| Speaker: | Erin V. Iski (University of Tulsa, Department of Chemistry and Biochemistry, Tulsa, Oklahoma/USA) |
| Abstract: | Often, pristine molecular resolution on metal surfaces necessitates the use of low temperature, ultra-high vacuum STM (LT-UHV STM). Importantly, it is also possible to study the assembly of molecules and atoms with liquid and electrochemical STM (EC-STM) to bridge the temperature and pressure gap of ultra-high vacuum studies and to take measurements under more realistic conditions. The first investigation focuses on the EC-STM study of five simple amino acids (AAs), and the means by which these molecules interact with a Au(111) surface. Using EC-STM under relevant biological conditions, the amino acids were shown to have a considerable interaction with the underlying surface. In some cases, the amino acids trapped diffusing adatoms to form Au islands and in other cases, they assisted in the formation of magic gold fingers. Importantly, these findings have also been observed under UHV con |
| Date: | Tue, 22.03.2022 |
| Time: | 16:00 |
| Location: | Tuesday, 22th March 2022, 16:00 s.t. TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner HauptstraÃe 8-10 Yellow Tower âBâ, 5th floor, SEM.R. DB gelb 05 B; The seminar will be also held a |
| Contact: | Univ.Prof. U. Diebold |
| CIPT-FOPT discrepancy problem |
| Speaker: | Miguel Benitez-Rathgeb (Vienna University) |
| Abstract: | The discrepancy between Fixed-Order Perturbation Theory (FOPT) and Contour-Improved Perturbation Theory (CIPT)
for the hadronic tau decay constitutes a major theoretical uncertainty for strong coupling determinations from hadronic tau decay spectral data.
I will introduce a scheme for a renormalon-free gluon condensate (GC) matrix element, which is capable of resolving the FOPT-CIPT discrepancy problem.
Furthermore I will talk about different methods of obtaining a norm for the GC, which is needed in the new GC scheme, and show first results of phenomenological applications.
In this context I will revisit studies from the past and discuss the implications of our new scheme on the strong coupling predictions. |
| Date: | Tue, 22.03.2022 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schrödinger-HS, Fakultät für Physik, Boltzmanngasse 5, 5. Stock sowie ZOOM https://univienna.zoom.us/j/93427906843?pwd=YjhSejdUVW16QjVQYUh5TVNSNFNhQT09 |
| Contact: | A. Hoang, M. Procura |
| An analogue view on quantum vortex dynamics |
| Speaker: | Sebastian Erne (TU Wien Atominstitut) |
| Abstract: | Ultracold atoms and their non-equilibrium evolution present an ideal platform to study fundamental processes of quantum field theory and the relaxation dynamics of quantum many-body systems. Following a general introduction to continuous analogue quantum simulators, I will present some recent results on vortex dynamics in Bose Einstein condensates, in particular the sound-ring radiation of dense vortex clusters and the superradiant instability leading to the decay of multiply quantized vortices. For the latter, a meta-stable bound state for vortices of the same circulation is found in finite size systems. A WKB analysis captures the relevant dynamical processes, consistent with full simulations of the stochastic Gross-Pitaevskii equation. |
| Date: | Wed, 23.03.2022 |
| Time: | 16:15 |
| Duration: | 45 min |
| Location: | ATI Hörsaal/ https://tuwien.zoom.us/j/93672218922?pwd=dEZNQ2liVzRNNURvNmVWVE5KUWRiQT09 |
| Contact: | Jörg Schmiedmayer |
| The localization and propagation of high-frequency electromagnetic waves |
| Speaker: | Abraham Harte (Dublin City University, Ireland) |
| Abstract: | Every textbook on general relativity states that light propagates along null geodesics.Although there are many senses in which this is true at
sufficiently-high frequencies,it breaks down more generally.Different notions of "propagation direction" also become distinct at lower frequencies. This talk will focus on the motion "as a whole" of electromagnetic pulses with large(but not infinitely-large) frequencies.
Angular momentum then affects the motion,resulting in null but non-geodesic trajectories.Precise answers depend, however,on what exactly is meant by the "pulse as a whole:"its centroid.There are many centroid definitions which appear to be reasonable,but surprisingly,some of these appear to be nowhere near the pulse itself!This turns out to be an unphysical artifact of the high-frequency approximation. Although massless spinning wavepackets appear generically in the usual. . . |
| Date: | Thu, 24.03.2022 |
| Time: | 15:00 |
| Duration: | 60 min |
| Location: | ZOOM https://univienna.zoom.us/j/6540036841?pwd=SytyVkZJZzNyRG9lMm13ejlHeHRRUT09 Meeting ID: 654 003 6841 Passcode: Gs4brS |
| Contact: | P. Chrusciel, D. Fajman |
| Speaker: | Lukas Schleicher (Institut Néel Grenoble/Karlsruhe Institute of Technologie) |
| Abstract: | Silicon carbide nanowires show a strong interaction with focused light beams even when the nanowireâs dimensions are in the sub-wavelength regime of the light. Using a micro cavity allows to reach a ultra strong coupling regime. As part of my master thesis I could investigate in this setup some specific nanowire diameters which showed peculiar behavior in the shift of the cavity resonance. To see these effects, the readout optics had to be improved since this behavior is strongly dependent on the polarisation of the light.
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| Date: | Fri, 25.03.2022 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Seminarraum ATI |
| Contact: | Julian Leonard |
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