by Daniel Grumiller & Beatrix Hiesmayr & Maximilian Attems

Di 12:30-13:30

abwechselnd auf der

TU Wien (E136, 10. Stock (gelb))

oder der

Uni Wien (Boltzmanngasse 5, 5.Stock, gr. Seminarraum)


Wie auf vielen Elite Unis praktiziert, wollen wir ein Lunch-Seminar etablieren, das aktuelle Themen der Theoretischen Physik, die auf unseren Unis von DiplomandInnen, DoktorandInnen und Postdocs behandelt werden, aufgreifen.

Das Niveau soll so sein, dass jeder Student und jede Studentin am Ende des Studiums dem Vortrag folgen kann! Die Vortragenden werden auch ermutigt, keinen "perfekten" Vortrag zu halten, sondern haupsächlich zu motivieren, warum sie dieses Thema gewählt haben, und dabei dürfen auch durchaus offene Fragen und Probleme behandelt werden.

Damit es zu praktisch keinen "Zeitverlust" kommt, wird gratis ein Mittagessen (Pizza,...) zur Verfügung gestellt.

We want to establish a Graduate Student Lunch Club as praticed at other institutions like MIT.

The seminars are designed for graduate students and should be accesible to all students. Students before their Diploma are particularly encouraged to attend so that they may learn about research begin performed on both universities. Speakers are encouraged to focus also on their motivation why they chose this particular topic and raise open questions.

In order to avoid any "loss of time" we provide a free lunch (pizza,...).

Wie kann ich teilnehmen?/

How can I join?

Einfach erscheinen! Falls man per Email informiert werden möchte, besuche die Seite Mailinglist oder Mail an Beatrix.Hiesmayr et oder an grumil et

Just attend! To receive infos per email got to Mailinglist or drop an email to Beatrix.Hiesmayr et or grumil et


7. Oktober 2008

TU Wien

Gerd Ch. Krizek (Uni Wien)

Gedanken Experiments for Quantum Mechanics and Gravitation

Quantum mechanics and the general theory of relativity are the pillars of modern physics and both nearly 100 years old. But it is still one of the biggest challenges to unify them. We will not give an answer to problems of the unification, but want to give an insight in problems that occur when these models overlap. We will formulate three Gedankenexperiments in which gravity and quantum mechanics and alternative models of quantum mechanics will play a role to give a better understanding on the problems in this complex field.

14. Oktober 2008

Uni Wien

Niklas Johansson (Uppsala University)

Recent developments in 3 d gravity

Gravity in three dimensions strikes a balance between models that are tractable and models that are relevant. It may exhibit black hole solutions, graviton modes and asymptotically Anti-deSitter solutions. There have been great efforts in trying to quantize 3D gravity, but the results remain unsatisfactory. In this talk we review a recent approach to 3D gravity called "chiral gravity". This model has peculiar features giving some hope that it is particularly simple to quantize. However, there has been a sometimes heated debate regarding the stability of the model. We explain why, and give an updated status report.

21. Oktober 2008

TU Wien

Nicolai Friis (Uni Wien)

Relativistic effects in quantum entanglement

Entanglement of quantum systems has proven to be a vital resource in information processing protocols, such as quantum teleportation and quantum cryptography, and the investigation of fundamental properties of nature via Bell's theorem. Much effort has therefore been put into describing and quantifying entanglement and the mechanism that lead to it's diminishment. Thus the next logical step is to continue the analysis in a relativist setup. We will discuss the effect of Lorentz transformations on quantum systems in form of the so called Wigner rotations and their influence on entanglement. We will present the possibilities and difficulties arising from this relativistic description.

28. Oktober 2008

Uni Wien

Daniel Blaschke (TU Wien)

Towards renormalizable models for gauge fields in non-commutative space
When trying to construct a quantum field theory on non-commutative space-time, e.g. by employing the so-called Groenewold-Moyal star product, one inevitably runs into the infamous UV/IR mixing problem where new kinds of non-local IR divergences prevent the model from being renormalizable. In fact, so far only some modified scalar field theories on Euclidean non-commutative spaces have been found to be renormalizable by successfully circumventing problems due to UV/IR mixing. In this talk I give an introduction to this interesting field of research and present a promising candidate for a renormalizable non-commutative gauge theory.

4. November 2008

TU Wien

Robert Schoefbeck (HEPHY)

Early SUSY searches at CMS
This is not going to be a purely experimental talk. I will review the basic motivation for supersymmetry and its phenomenological implications. We will discuss the current situation in experiment and the theorists hope for future findings at the LHC in the main SUSY channels. This talk is intended as a teaser for the exciting physics ahead, and I try to shed light on some aspects of the most interesting correlations among theory, phenomenology and the every-day work of the particle physicist.

11. November 2008

Uni Wien

Rene Meyer (MPI Munich)

The D3-D7 model of AdS/CFT with Flavour
I will give a pedagogical introduction into the D3-D7 model of holographic (N=2 supersymmetric) flavour physics, as well as talk about recent results concerning the behaviour of this system in the presence of external electric and magnetic fields.

18. November 2008

TU Wien

Philipp Krammer (Uni Wien)

Geometric entanglement witnesses
A challenge in quantum information theory is the detection of entangled states on a finite dimensional Hilbert space. Useful tools for this purpose are entanglement witnesses; they provide a geometrically intuitive method to detect entanglement. I will explain the concept of entanglement witnesses and how to combine it with the notion of Bloch decompositions. Geometric entanglement witnesses are a simple example for a geometrical construction of witnesses. I will show how to use "shifts" of such witnesses in order to detect entanglement and to find the set of separable states for a convex subset of states.

25. November 2008

Uni Wien

Andreas Kastner (Uni Wien)

Semileptonic Kaon decays in Chiral perturbation theory
Due to quark confinement QCD, the quantum field theory of strong interactions, becomes non-perturbative at low energy. In order to obtain predictions for strong processes in the energy region of confinement, one can use a so called effective field theory. Chiral perturbation theory (ChPT), the low-energy limit of the standard model, only makes use of the symmetries of the QCD Lagrangian and does not invoke the dynamics of quarks and gluons. We want to show the basic properties and problems of effective field theories by discussing the predictions of the standard model for specific kaon decays, the K_l3 decays, in ChPT, including isospin violating effects of strong and electromagnetic origin.

2. Dezember 2008

TU Wien

Florian Aigner (TU Wien)
Coherent scattering of fast atoms at surfaces
Diffraction of particles scattered at surfaces was among the key experiments establishing the quantum wave nature of matter. Atoms being diffracted at crystal surfaces exhibit intriguing diffraction patterns, closely related to those visible in double-slit experiments, which have been carried out using particles as heavy as fullerenes. Scattering of keV atoms at surfaces has recently been shown to be a powerful tool to investigate the structure of surfaces. Even in environments which would strongly suggest the dominance of decohering effects (hot surfaces, phonon vibrations) quantum coherent scattering patterns remain visible. This is especially remarkable, as the de Broglie wavelength of scattered atoms in the keV range is as low as a few picometers.

9. Dezember 2008

Uni Wien

Wolfgang Dungel (HEPHY)

Physics analysis at Belle
The aim of physics analysis is to match the predictions of theory with experimental results. At the collider experiment Belle in Tsukuba, Japan, the main focus lies in the investigation of the Cabbibo-Kobayashi-Maskawa matrix, which contains the only source of CP-violation within the standard model. This talk aims at presenting the Belle experiment and the basic aims and pitfalls in analyzing the data of particle physics experiments in a very general way. Afterwards, a more detailed view of one specific analysis will be given, which centers on the investigation of 'B0-> D* l nu' decays.

16. Dezember 2008

TU Wien

Narit Pidokrajt (Stockholm University)

Black Hole Thermodynamics à la Information Geometry
In this talk we will discuss the use of information (a.k.a. Ruppeiner) geometry to understand thermodynamics of various black holes e.g. 2D dilaton black holes, Myers-Perry black holes in higher dimensions among others. It has been known that the geometrical theory of thermodynamics provides an alternative and elegant route to obtain insight into thermodynamics through Riemannian geometry. Its power is due to the fact that the information metric together with its associated curvature and signature encodes many aspects of thermodynamics consistent with the known results in the literature. Since we do not yet have a settled statistical mechanics of black holes, the information geometry of black hole thermodynamics also paves a road to a (possibly) new way of understanding of the microscopic degrees of freedom of the black holes. There are many potential applications of this geometric method as there are emerging black objects in higher dimensions and black hole analogs which require new perspectives in order to better understand them.

13. Jänner 2009

Uni Wien

Dionysis Triantafyllopoulos (ECT Trento and TU Wien)

Parton Saturation in Quantum Chromodynamics
When we perform a series expansion in a Quantum Field Theory, large logarithms may appear in the perturbative coefficients in certain kinematical regions. Such a situation arises in Quantum Chromodynamics when we consider the scattering between partons at large center of mass energy and at a fixed momentum transfer. A resummation must be performed and the resulting total cross section rises as a power of the energy. At even higher energies nonlinear phenomena take place which lead to the unitarization of the cross section and the saturation of the hadronic wavefunction.

20. Jänner 2009

TU Wien

Harald Ita (UCLA)

One-Loop Multi-Parton Amplitudes for the LHC
We discuss the computation of one-loop QCD scattering amplitudes with BlackHat, a numerical program based on on-shell methods. We report scaling properties with increasing numbers of external partons and about numerical stability of the implementation. We conclude with first results from one-loop amplitudes needed for computing W,Z + 3 jet cross sections at the LHC to next-to-leading order in the QCD coupling.

27. Jänner 2009

Uni Wien

Andres Collinucci (TU Wien)

F-theory: Introduction and recent developments
Fourteen years ago, string theory underwent a major paradigm shift when techniques were developed to study the theory non- perturbatively, i.e. in its strongly coupled regime. More specifically, the introduction of D-branes and eventually M-theory opened up windows that relate the different versions of string theory, in different corners of its parameter space. A year after the idea of M-theory was conceived, Vafa developed what can be thought of as its obscure partner, known as "F-theory". Although it is less understood conceptually, F-theory is a more practical tool for model building, i.e. for trying to make contact with the standard model. Curiously, the year 2008 has seen a revival of "F-theory", as new results have emerged in the direction of model building.
In this talk, I will give an overall rough picture of M-theory and F- theory without assuming prior knowledge of string theory. Then, as time permits, I will show an explicit F-theory toy model. Finally, I will summarize the most recent developments in this branch.


Current programme of the Vienna Theory Lunch Club