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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 |
| 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 |
| 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 |
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