CPT

Calendar of Physics Talks Vienna

Matrix models of fuzzy field theories
Speaker:Jurai Tekel (Comenius University Bratislava)
Abstract:We introduce fuzzy field theories and give an overview of their spontaneous symmetry breaking patters. Fuzzy spaces enjoy a nontrivial short distance structure, which is reflected in some surprising ways to break the symmetry of a field theory. We then give a description of these theories in terms of hermitian matrix models. These models are a generalization of the standard random matrix models with extra terms in the probability distribution due to the kinetic term of the field theory. We present several possible ways how to deal with this modification and show to what extent they describe the desired properties of the corresponding field theory.
Date: Tue, 16.01.2018
Time: 14:00
Duration: 60 min
Location:TU Wien, Freihaus, SEM 136, 10. Stock, Wiedner Hauptstr. 8-10, 1040 Wien
Contact:S. Fredenhagen, D. Grumiller, H. Steinacker

Surface Science Approach to Understand Corrosion and Inhibition
Speaker:Frank Uwe Renner (Hasselt University, Institute for Materials Research (IMO) & IMOMEC, Diepenbeek/Belgium)
Abstract:Understanding of electrochemical (wet) corrosion processes constitutes a complex challenge with its dependence on substrate and environment chemistry, surface morphology, and eventual confinement. With a surface science approach we aim to reduce the complexity of corroding systems to well controlled initial states in addition to using in-situ techniques and high-resolution characterization. In this presentation I will provide two example cases. Dealloying of binary noble metal alloys in combination with a well-controlled approach to apply molecular inhibitor films provides unprecedented insights in corrosion inhibition. In-situ AFM allows to follow the initial steps of dealloying. Second, Fe-based bulk metallic glasses, so-called amorphous steels offer a very homogeneous elemental distribution in the starting material. The influence of even nanometer-scale fluctuations in the local compo
Date: Tue, 16.01.2018
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:Univ.Prof. Markus Valtiner

New perspectives in QCD with jet substructure
Speaker:Gregory Soyez (CNRS, Paris)
Abstract:im Rahmen des Teilchenphysikseminars
Date: Tue, 16.01.2018
Time: 16:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:H. Neufeld, S. Plätzer

Nonlinear Interactions of Gravitational Waves
Speaker:Stefan Palenta (Vienna)
Abstract:After an introduction on gravitational waves and nonlinear effects in general, the talk will present the foundations of a new solution technique for the characteristic initial value problem of colliding plane gravitational waves. Assuming plane symmetry, the Einstein equations essentially reduce to the Ernst equation. In the course of the inverse scattering method this nonlinear PDE is tranlated first into an overdetermined linear system of differential equations and secondly into a Riemann-Hilbert problem. Ambiguities in this Riemann-Hilbert problem's solution lead to the construction of families of exact spacetimes generalising the proper solution to the initial value problem. Therefore the presented technique also serves as a solution generating technique. The method is exemplified by generalising the Szekeres class of colliding plane wave spacetimes. A new type of circularly . . . .
Date: Thu, 18.01.2018
Time: 14:00
Duration: 60 min
Location:Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien
Contact:P.T. Chrusciel

Colloquium: On the interpretation of the Top Quark Mass from Reconstruction
Speaker:Prof. André Hoang (University of Vienna)
Abstract:The currently most precise measurements of the top quark mass are obtained from kinematic reconstruction obtained at hadron colliders. The observables designed to make these measurements cannot be calculated using analytic methods in QCD and therefore reply on multipurpose Monte-Carlo event generators. As a consequence, the interpretation of the measured top quark masses is theoretically difficult and still an open issue. In my talk I explain the theoretical issues inherent to this problem. It is currently also not yet fully understood, up to a conceptual upper bound, how large the uncertainty is when one interprets the result as measurements of the pole mass. [abridged]
Date: Fri, 19.01.2018
Time: 10:30
Duration: 60 min
Location:Wohllebengasse 12-14
Contact:Josef Pradler

Extremal CFTs with small central charge
Speaker:Francesca Ferrari (Amsterdam)
Abstract:In the talk I will review the different properties of 2d extremal chiral (super)conformal field theories with central charge smaller or equal to 24. These are theories whose only operators with dimension smaller or equal to c/24 are the vacuum and its Virasoro descendants. One of the most famous example is the Monster CFT. Its twining functions can be completely constructed from the vacuum structure and the modular properties of the functions via a Rademacher sum (Farey tail). Following a recent work in collaboration with Sarah Harrison, I will investigate the extent to which such a property holds for other known extremal theories.
Date: Fri, 19.01.2018
Time: 14:00
Duration: 60 min
Location:SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna)
Contact:Timm Wrase

Many-body cavity QED with multimode resonators
Speaker:Benjamin Lev (Stanford University)
Abstract:We will present our first experiments involving multimode cavity QED, wherein the cavity-mediated atom-atom interaction is dramatically modified compared to that in a single-mode cavity. We will report on measurements that demonstrate that strong, tunable-range photon-mediated interactions can be engineered between atoms and spins in such a cavity. These results pave the way for future experimental access to nontrivial phase transitions in driven-dissipative quantum systems, synthetic dynamical gauge fields, and the ability to study novel non-equilibrium spin glasses and quantum neuromorphic computation.
Date: Fri, 19.01.2018
Time: 15:30
Location:Atominstitut, Hörsaal, Stadionallee 2, Wien 2
Contact:J. Schmiedmayer