Calendar of Physics Talks Vienna

Calabi-Yau compactifications and supersymmetric gauge theory
Speaker:Johanna Knapp (TU Wien)
Abstract:im Rahmen des Seminars für Mathematische Physik: The mathematics of Calabi-Yau spaces plays a crucial role in the context of string theory. In this talk I present a supersymetric gauge theory in two dimensions (the gauged linear sigma model) which encodes information about Calabi-Yaus. I will focus in particular on new methods for computing quantum corrections in string compactifications, most notably the hemisphere partition function, which computes the quantum corrected central charge of D-branes on Calabi-Yaus.
Date: Tue, 24.01.2017
Time: 14:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:S. Fredenhagen, H. Steinacker

Local Dzyaloshinskii-Moriya Interaction in Skyrmion Thin-Film Multilayers Measured
Speaker:Hans J. Hug (Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf/Switzerland)
Abstract:To understand and control skyrmions in spintronics applications will require quantitative magnetic measurements of their structure at nanometer scales and at RT, from substrate-based thin films with oxidation protection layers. We show how magnetic force microscopy techniques can achieve this. The Dzyaloshinskii-Moriya interaction (DMI) induced by the interfaces of thin-film structures supports skyrmions at room temperature [1]. The local and average DMI can be quantified from measured domain patterns, because the DMI coefficient D results from an equilibration of magnetostatic and wall energies. Local D values are obtained from matching simulated MFM profiles from skyrmions to measured MFM data. We use calibrated MFM tip transfer functions to calculate the MFM frequency shift profiles from model skyrmion magnetization distributions. We show skyrmions smaller than previously observed in
Date: Tue, 24.01.2017
Time: 16:00
Location:Technische Universität Wien, Institut für Angewandte Physik, E134 yellow tower „B“, 5th floor, Sem.R. DB gelb 05 B (room DB05L03), 1040 Wien, Wiedner Hauptstr. 8-10
Contact:Univ.Prof. Dr. Ulrike Diebold

Elektroweak Sudakov logarithms in e+e-→ t t
Speaker:Daniel Lechner (Univ. Wien)
Abstract:im Rahmen des Teilchenphysikseminars
Date: Tue, 24.01.2017
Time: 16:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:A. Hoang, H. Neufeld

Hyperon spectroscopy and production dynamics with PANDA at FAIR
Speaker:Dr. Karin Schönning (University Uppsala)
Abstract:One of the most challenging questions in contemporary physics is how and why the strong interaction confines the quarks into composite hadrons; either mesons (quark-antiquark) or baryons (three quarks). Hyperons are baryons where one (or several) light quark(s) are replaced by a heavier one(s). Strange hyperon spectroscopy and dynamics can provide keys to the strong interaction in the so far poorly understood confinement domain. Ever since first observed in experiment, hyperons have played an important role in our understanding of fundamental interactions. In the early days of particle physics, the newly discovered ground-state hyperons provided a key to the eight-fold way of the strong interaction from which the quark model emerged. In the same way, the excited hyperon spectra ... [full abstract available here https://indico.smi.oeaw.ac.at/event/214/]
Date: Wed, 25.01.2017
Time: 17:00
Duration: 60 min
Location:Stefan-Meyer-Institut, Boltzmanngasse 3, 1090 Wien, Seminarraum 3-2-08 (2. Stock)
Contact:Prof. Dr. Eberhard Widmann, Dr. Martin Simon

Analog models of Hawking and Casimir physics in atomic and optical systems
Speaker:Iacopo Carusotto (INO-CNR BEC Center, Trento)
Abstract:In this talk I will review the state of the art in the theoretical and experimental study of analog models of quantum field theories in flat, curved, or time-dependent backgrounds using condensed matter and optical systems. In the first part, I will focus on the theory of the stimulated and spontaneous Hawking emission of phonons in flowing fluids of ultracold atoms and of photons in semiconductor microcavities and I will outline the state of the art of experimental investigations. In the second part, I will introduce analogs of two-level emitters coupled to the quantum field and I will present recent works on the observable consequences of Casimir physics and of Ginzburg radiation processes for moving emitters. I will conclude with an outline of more speculative investigations in the direction of highlighting the back-reaction effect of Hawking emission onto a black hole horizon.
Date: Thu, 26.01.2017
Time: 14:00
Duration: 60 min
Location:Arbeitsgruppe Gravitation, Währinger Strasse 17, Victor-Franz-Hess-Hörsaal, Kavalierstrakt, 1. Stock
Contact:P.T. Chrusciel

One dimensional Bose Gas on an atom chip: Correlations in Momentum Space and Theoretical Investigation of Loss-induced Cooling
Speaker:Aisling Johnson (Laboratoire Charles Fabry de l'Institut d'Optique Graduate School )
Abstract:We present experimental and theoretical results on the ultracold one-dimensional (1D) Bose gases, trapped at the surface of a micro-structure. Second-order correlations in momentum space were measured. Our data span the weakly-interacting regime of the 1D Bose gas, going from the ideal Bose gas regime to the quasi-condensate. These measurements revealed bunching in both phases, while in the quasi-condensate off-diagonal negative correlations, a signature of the absence of long-range order in 1D, were revealed. These experimental results agree well with analytical calculations and exact Quantum Monte Carlo simulations. A second project focused on the cooling of such 1D gases. An alternative cooling scheme, based on non-selective removal of particles, was proposed and demonstrated by colleagues of the Atominstitut [1,2]. With classical field simulations we demonstrate the robustness of the non-thermal state arising from these losses: different modes indeed lose energy at different rates. We also demonstrate that a non-integrable system (two coupled gases with different mass) relaxes towards equilibrium when submitted to dissipation, thereby relating the previously demonstrated non-thermal state to the integrability of the one-dimensional Bose gas.
Date: Fri, 27.01.2017
Time: 15:30
Location:Hörsaal Atominstitut - Stationallee 2, 1020 Wien
Contact:Arno Rauschenbeutel