Calendar of Physics Talks Vienna

Generalized supergravity and non-abelian T-duality anomaly
Speaker:Linus Wulff (Masaryk University, Brno)
Abstract:I will describe how kappa symmetry of the Green-Schwarz superstring leads to the so-called generalized supergravity equations for the background fields. I will then focus on some interesting connections with non-abelian T-duality. Non-abelian T-duality is known to be anomalous for certain groups and I will show how the structure of the anomaly fits with the generalized supergravity equations. This analysis leads to an interesting way that the anomaly can cancel in certain cases.
Date: Tue, 17.04.2018
Time: 13:45
Duration: 60 min
Location:TU Wien, Freihaus, SEM 136, 10. Stock, Wiedner Hauptstraße 8-10, 1040 Wien
Contact:S. Fredenhagen, D. Grumiller

Acoustic Levitation: Recent Improvements, Do-It-Yourself Devices, and Applications in Display Technologies
Speaker:Marzo Asier (Ultrasonics and Non-destructive Testing, Dept. Mechanical Engineering, University of Bristol, United Kingdom)
Abstract:Acoustic Tweezers use sound radiation forces to trap and manipulate samples. They provide unique advantages such as high trapping force, support of numerous sample materials and operation in various media. Also, the available range of sound frequencies enable applications from the micrometre to the centimetre scale. Despite the advantages of Acoustic Tweezers, its progress has always been behind that of Optical Tweezers. In this talk, I will present recent advancements that have reduced the gap between acoustic and optical trapping, i.e. single-beam, wavelength-scale, and multi-particle acoustic trapping. Additionally, I will introduce DIY levitators that everyone can build at home. Finally, I will showcase some specific applications of acoustic levitation in display technologies.
Date: Tue, 17.04.2018
Time: 16:00
Location:Technische Universität Wien, Institut für Angewandte Physik, E134 yellow tower „B“, 5th floor, Sem.R. DB gelb 05 B (room number DB05L03), 1040 Wien, Wiedner Hauptstraße 8-10
Contact:Ao.Univ.Prof. Dr. M. Gröschl

Automating Calculations in Soft-Collinear Effective Theory
Speaker:Guido Bell (Univ. Siegen)
Date: Tue, 17.04.2018
Time: 16:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:A. Hoang, H. Neufeld

Asymptotics properties of the small data solutions of the Vlasov-Maxwell system in high dimensions
Speaker:Léo Bigorgne (Orsay)
Abstract:The Vlasov-Maxwell system is a classical model in plasma physics. Glassey-Strauss proved global existence for the small data solutions of this system under a compact support assumption on the initial data. They also established optimal decay rates for these solutions but not on their derivatives. We present here how vector field methods, developped by Christodoulou-Klainerman ([CK]) for the Maxwell equations (in 3d) and, more recently, by Fajman-Joudioux-Smulevici ([FJS]) for the Vlasov equation, can be applied to revisit this problem. In order to adapt the results of [CK] in high dimensions, and then obtain the optimal pointwise decay estimates on the null components of the electromagnetic field, we study the Vlasov-Maxwell system in the Lorenz gauge. We extend the techniques of [FJS] as we do not use a hyperboloidal foliation (and we then do not need any compact support assumption in space on the initial data) thanks to a new decay estimate for the velocity average of the Vlasov field. It allows us, by making crucial use of the null properties of the system, to remove all compact support assumptions on the initial data and to obtain optimal decay rates for the derivatives of the solutions. The work on the 3d case is in progress.
Date: Thu, 19.04.2018
Time: 14:00
Duration: 60 min
Location:Arbeitsgruppe Gravitation, Währinger Straße 17, SR 218, 2. Stock
Contact:P. Chrusciel, D. Fajman

Metallic Quantum Ferromagnets
Speaker:Manuel Brando (Max Planck Institute for Chemical Physics of Solids, Dresden)
Abstract:In my talk I will review studies on quantum criticality with focus on metallic ferromagnets. The existence of a ferromagnetic quantum critical point has been a matter of discussion as long as 40 years ago, but had been dismissed in the past 15. Recently, several ferromagnetic metals have been tuned across the ferromagnetic quantum phase transition and studied with modern techniques. At the quantum phase transition astonishing discoveries were made that are extending our understanding of ferromagnetic quantum criticality.
Date: Fri, 20.04.2018
Time: 14:30
Duration: 45 min
Location:Seminar Room CBEG02 (387, Photonics); Gußhausstraße 27
Contact:Andrei Pimenov