CPT

Calendar of Physics Talks Vienna

Problems in the Lifshitz theory of dispersion forces
Speaker:Vladimir M. Mostepanenko (Russian Academy of Sciences, Saint Petersburg, Russia)
Abstract:The Lishitz theory describes the van der Waals and Casimir forces which arise between two closely spaced material bodies due to the zero-point and thermal fluctuations of the electromagnetic field. A lot of precise measurements of the Casimir force performed during the last two decades revealed a puzzle. The theoretical predictions have been found in agreement with the measurement data only under a condition that in computations one disregards the relaxation properties of conduction electrons for metals and the dc conductivity for dielectrics. On the theoretical side it was found that if both these effects are included, one arrives to contradictions with thermodynamics. Possible resolution of this puzzle is discussed.
Date: Mon, 21.01.2019
Time: 14:15
Duration: 60 min
Location:TU Wien, Freihaus HS 7, Wiedner Hauptstr. 8-10, 2nd floor, 1040 Wien
Contact:Anton Rebhan

Exceptional geometry of supersymmetric AdS vacua
Speaker:Emanuel Malek - Max Planck Institute for Gravitational Physics, Potsdam
Abstract:In this talk I will show how exceptional field theory can be used to construct 1/2-maximally supersymmetric AdS vacua of 10/11-dimensional supergravity and their consistent truncations.In particular I will show how to easily recover the class of infinitely-many supersymmetric AdS_7 vacua of massive IIA and AdS_6 vacua of IIB which were recently constructed in the literature.Next I will show how this framework can be used to immediately obtain the "minimal" consistent truncation around these AdS vacua in which only the gravitational supermultiplet of the lower-dimensional supergravity is kept.Finally I will classify all possible consistent truncations around these AdS vacua containing additional matter multiplets.I will thus show there are no consistent truncations with vector multiplets for the AdS_7 vacua with Roman's mass and give precise differential conditions for the AdS_6 vacua ...
Date: Tue, 22.01.2019
Time: 13:45
Duration: 60 min
Location:TU Wien, Getreidemarkt 9, Maschinenbaugebäude, 1. Stock, HS Kleiner Schiffbau
Contact:S. Fredenhagen, D. Grumiller

Removing infrared divergences from perturbative amplitudes
Speaker:George F. Sterman (SUNY, Stony Brook)
Abstract:4. Vorlesung im Rahmen der Schrödingen-Gastprofessur: It may be useful to separate perturbative amplitudes into universal infrared-sensitive terms, which sometimes can be computed exactly, plus infrared-finite remainders, which can in principle be computed numerically. Two-loop scalar diagrams illustrate how such a procedure could work.
Date: Tue, 22.01.2019
Time: 16:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:A. Hoang, H. Neufeld

Band structure of HgTe-based topological insulators
Speaker:Sergey Tarasenko (Ioffe Institute, St. Petersburg, Russia)
Abstract:Quantum wells (QWs) and thin films based on band-inverted material HgTe have been attracting growing attention since they can realize 2D and 3D topological insulators. Here, we discuss the fine structure and optical properties of the bulk and edge states in 2D topological insulators based on HgTe QWs. A natural interface and bulk inversion asymmetry, reflecting the real atomistic structure of zinc-blende-type QWs, leads to the spitting of the Dirac states in HgTe QWs. The inversion symmetry drastically modifies the dispersion, magnetic and optical properties of the helical edge states. In particular, it enables the electro-dipole optical transitions between the spin branches of the edge channel and gives rise to the linear and circular dichroism associated with the edge states as well as the circular and linear edge photocurrents.
Date: Wed, 23.01.2019
Time: 16:00
Location:Freihaus, Sem.R. DC rot 07 OG
Contact:Andrei Pimenov