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Calendar of Physics Talks Vienna
| Symmetries of Strings and Branes (part 2 of 4) |
| Speaker: | Peter West (King’s College) |
| Abstract: | I will begin by explaining electro-magnetic duality symmetries in the context of supersymmetric Yang-Mills theories. I will then discuss S, T and U dualities of string theory and their implications for branes. The conjectured E11 symmetry will also be considered. |
| Date: | Tue, 03.05.2011 |
| Time: | 10:00 |
| Duration: | 120 min |
| Location: | ESI (Boltzmanngasse 9, Erwin Schrödinger Lecture Hall) |
| Contact: | Nils-Ole Walliser (TU Wien) |
| LPVs in NGC147 and NGC185 - Probing a new tool to measure extragalactic distances |
| Speaker: | Denise Lorenz (University of Vienna) |
| Abstract: | Most of the variable stars change their brightness periodically and can therefore be classified according to their periods and amplitudes. Of special interest are variables that increase their mean luminosity according to the length of their period, as has been found for Cepheid stars. They can be used to establish a period-luminosity-relation (PLR) which enables us to determine the distance just by measuring the period of the star. Huge surveys of variable stars in the Magellanic Clouds - the neighbourhood of the Milky Way - revealed sequences of Long Period Variables (LPVs) in a period-luminosity-diagram. These findings encouraged the search of a PLR valid for LPVs and the investigation of its universality. LPVs are intrinsically brighter than Cepheid variables, hence, at greater distances LPVs are still observable. Therefore, a universal LPV-PLR would allow to measure distances of all stellar systems in which we are able to detect LPVs. Meanwhile, technical progress allows to resolve single stars in galaxies not only in the surroundings of the Milky Way but also at a distance of the Andromeda Galaxy and beyond. Our work describes the search of LPVs in the two neighbouring dwarf galaxies of Andormeda, NGC147 and NGC185, and their use in order to establish a universal PLR. |
| Date: | Tue, 03.05.2011 |
| Time: | 12:30 |
| Duration: | 60 min |
| Location: | TU Wien (Wiedner Hauptstr. 8-10, yellow area, 10th floor, seminar room E136 ) |
| Contact: | Sabine Ertl |
| Coupling effects between Lattice dynamics and Magnetism in Multiferroic Manganites |
| Speaker: | Sven Issing (Universität Würzburg) |
| Abstract: | Multiferroic materials have received quite a lot of attention in the recent years due to their intriguing properties of intimately coupled dielectric and magnetic properties [1]. Among these materials the orthorhombic perovskites RMnO3 (R = Eu1-xYx, Gd, Tb) represent a model system, which allows the study of the role of crystalline distortion on
the frustrated magnetic behaviour leading to the appearance of the magneto-electric effect, i.e. ferroelectricity. The latter can be suppressed or even switched by magnetic fields [2]. Optical spectroscopy in the Far Infrared- and Terahertz regime and Raman
spectroscopy gather complementary information about the lattice dynamics and unique elementary excitations of these magneto-electrically coupled systems (socalled “Electromagnons”) [3,4]. Our investigative goal is the systematic study of polar (i.e. Infrared-active) and unpolar (i.e. Raman-active) phonons and their correlation to
the magnetic order of these systems. Two important coupling mechanisms were analyzed and will be presented here: Spin-Phonon Coupling [5,6] and Electromagnon-Phonon Coupling. Both effects give deep insights into the dynamic behaviour of this highly interesting material.
[1] S.W. Cheong and M. Mostovoy, Nat. Mater. 6, 13 (2007)
[2] T. Kimura et al., Nature 426, 55 (2003)
[3] S. Issing et al., EPJ B 73, 353-360 (2010)
[4] A. Pimenov et al., Nat. Phys. 2, 97-100 (2006)
[5] S. Issing et al., PRB 81, 024304 (2010)
[6] S. Issing et al., EPJ B 78, 367-372 (2010) |
| Date: | Wed, 04.05.2011 |
| Time: | 16:00 |
| Location: | Freihaus Seminarraum 138B, Turm C, 7. OG (rote Leitfarbe), Wiedner Hauptstraße 8-10, 1040 Wien |
| Contact: | Andrei Pimenov |
| Symmetries of Strings and Branes (part 3 of 4) |
| Speaker: | Peter West (King’s College) |
| Abstract: | I will begin by explaining electro-magnetic duality symmetries in the context of supersymmetric Yang-Mills theories. I will then discuss S, T and U dualities of string theory and their implications for branes. The conjectured E11 symmetry will also be considered. |
| Date: | Wed, 04.05.2011 |
| Time: | 16:00 |
| Duration: | 120 min |
| Location: | ESI (Boltzmanngasse 9, Erwin Schrödinger Lecture Hall) |
| Contact: | Nils-Ole Walliser (TU Wien) |
| Neutrinos - Astrophysical and Particle-Physics Messengers |
| Speaker: | Georg Raffelt (MPI, München) |
| Abstract: | 1. Vorlesung im Rahmen der Schrödinger-Gastprofessur 2011 |
| Date: | Thu, 05.05.2011 |
| Time: | 14:15 |
| Duration: | 90 min |
| Location: | Fakultät für Physik, Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | W. Grimus, H. Neufeld |
| Elastic spheres on circular orbits |
| Speaker: | Stephan Broda (Vienna) |
| Abstract: | Im Rahmen des Literaturseminars |
| Date: | Thu, 05.05.2011 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe: Gravitation, Währinger Strasse 17, Seminarraum A, 2. Stock |
| Contact: | R. Beig |
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