Vienna Theory Lunch Seminar
by Sabine Ertl, Sebastian Frank, Philipp Köhler, Karoline Mühlbacher and Florian Preis
TU Wien ( Wiedner Hauptstr. 8-10, yellow area,
10th floor, seminar
room E136 )
Uni Wien ( Boltzmanngasse 5, 5th floor, Schrödinger HS / large seminar room )
We thank our kind
Wie auf vielen Universitäten
praktiziert wollen wir ein Lunch-Seminar etablieren, das aktuelle Themen der
Theoretischen Physik, die von DiplomandInnen, DoktorandInnen und PostDocs
behandelt werden, aufgreift.
Das Niveau soll so gewählt
werden, dass jeder Student und jede Studentin am Ende des Studiums dem
Vortrag folgen kann. Die Vortragenden werden ermutigt keinen
"perfekten" Vortrag zu halten, und sollen hauptsächlich Ihre
Motivation, warum sie dieses Thema gewählt haben, wiedergeben. Dabei dürfen
durchaus offene Fragen und Probleme behandelt werden.
Damit es zu keinem "Zeitverlust" kommt, wird Mittagessen (Pizza, Sushi) gratis zur Verfügung gestellt.
We want to
establish a lunch seminar
as practiced at other universities.
The focus is on recent theoretical research done by Master students, PhDs and PostDocs.
is designed for graduate students but should also be comprehensible to advanced undergraduate
students. Pre-diploma students are particularly encouraged to attend so that they receive
an overview of research activities conducted at both universities. Speakers are also encouraged to focus on their
motivation for choosing their particular topic and to present
In order to avoid any "loss of time" we provide a free lunch (pizza, sushi).
Wie kann ich teilnehmen?
How can I join?
Einfach erscheinen! Um per Email informiert zu werden, bitte in die Mailinglist eintragen oder Mail an fpreis at hep.itp.tuwien.ac.at oder an philipp.martin.koehler at univie.ac.at
Just attend! To receive informations via email go to the Mailinglist or drop an email to fpreis at hep.itp.tuwien.ac.at or philipp.martin.koehler at univie.ac.at
11 Oct 2011
Patrick Otto Ludl
Abstract: The fact that at least two of the three known active neutrinos have non-vanishing masses is the most important evidence for physics beyond the standard model of particle physics. In the same way as the introduction of quark mass terms leads to quark mixing, the introduction of neutrino mass terms leads to lepton mixing in charged current interactions. While in the quark-sector the mixing matrix is close to the unit matrix, in the lepton sector this is not the case. In fact in the lepton sector two of the three mixing angles are quite large. An interesting possibility to "explain" these large values for the mixing angles is to impose certain symmetries on the actions of the leptonic and scalar sector, the most popular symmetry groups being finite groups. After an introduction to the physics of lepton mixing we will take a look on the mathematics of finite groups. Finally we will study some simple models using finite groups in order to reproduce some of the features required to accommodate the experimental results.
18 Oct 2011
We start by reviewing experimental hints that suggest that the quark gluon plasma, which can be produced in heavy
ion collisions taking place at RHIC (Relativistic Heavy Ion Collider) and LHC (Large Hadron Collider) is a
strongly coupled liquid rather than a weakly coupled gas. In order to study aspects of this strongly coupled
matter we introduce holography also known as gauge gravity duality and calculate the shear viscosity. Finally we
discuss the possibilities of studying anisotropic systems within this framework.
25 Oct 2011
I will review the AdS/CFT correspondence, motivating the duality from the perspective of the black hole information
problem. After a thorough introduction, I will explain a test of the holographic nature of the correspondence and
show higher dimensional local physics emerging in the limit that the AdS radius becomes large (equivalently,
$N_c\rightarrow\infty$). If time allows, I will talk about obstructions to the construction at finite N.
8 Nov 2011
Abstract: Current attempts to probe general relativistic effects in quantum mechanics focus on precision measurements of phase shifts in matter-wave interferometry. Yet, phase shifts can always be explained as arising due to an Aharonov-Bohm effect, where a particle in a flat space-time is subject to an effective potential. Here we propose a novel quantum effect that cannot be explained without the general relativistic notion of proper time. We consider interference of a "clock" - a particle with evolving internal degrees of freedom - that will not only display a phase shift, but also reduce the visibility of the interference pattern. According to general relativity proper time flows at different rates in different regions of space-time. Therefore, due to quantum complementarity the visibility will drop to the extent to which the path information becomes available from reading out the proper time from the "clock". Such a gravitationally induced decoherence would provide the first test of a genuine general relativistic notion of proper time in quantum mechanics.
22 Nov 2011
Abstract: The primary goal of current particle
physics experiments is to verify/disprove the Standard Model or to find hints for new theories.
To be able to do that, a huge number of events has to be recorded and analyzed. Tracks and properties
(momentum, type, location of production point (vertex)...) of particles have to be reconstructed from the
recorded data to be able to analyze them for statistical deviations from the predictions of current models.
A considerable background generated by several effects and geometrical limitations of the detector
complicate the task of track reconstruction.
In this talk the first step of pattern recognition, the track finding will be presented and explained
using the upcoming Belle II - Silicon Vertex Detector at KEK (Japan) as an example. Several common and newer
algorithms for that task will be briefly explained.
29 Nov 2011
Abstract: At very high densities, the ground state of quark matter is a colour superconductor in the "colour flavour locked" (CFL) state. In nature, such densities are realized in compact stars. Since CFL is also a superfluid, properties of compact stars might depend on the hydrodynamics of CFL quark matter. I will therefore discuss, how superfluid hydrodynamics in such a system emerge from the corresponding microscopic theory.
6 Dec 2011
Abstract: A quark-gluon plasma formed in heavy-ion collision experiments may feature initial momentum-space
anisotropies. Such an anisotropic QGP exhibits a direct photon spectrum which is strongly dependent
on the emission angle. Using models for the time evolution of the plasma, a time-dependent photon
signal can be calculated whose length is on the order of yoctoseconds. Placing a detector at lower
angles close to the beam axis, a photon signal shows a remarkable double-peak shape. In this talk, I
will explain the mechanisms that give rise to double pulses, how the effect of such pulses could be
observed, and what these pulses can tell us about the quark-gluon plasma itself.
13 Dec 2011
!!!TU Wien at 11:45!!!
Abstract: After a short introduction to QCD and current issues about dense quark matter,
I will explain a new state of QCD matter, Quarkyonic matter,
which was recently proposed by McLerran and Pisarski.
In Quarkyonic matter, quark density is so high that
the quarks are released from the baryons,
nevertheless excitation modes are confined.
After explaining its basic concepts, I will discuss the emergence of the
interweaving chiral spirals which spontaneously break the translational,
rotational invariance, and the chiral symmetry near the Fermi surface.
Its potential relevance to future heavy ion experiments is briefly discussed.
10 Jan 2012
Abstract: The general relativistic oscillations of a thin accretion disk around compact astrophysical objects are
analyzed. These objects interact with the surrounding medium through non-gravitational forces, modeled via a
friction force and a random force respectively. The dynamics of the stochastically perturbed disk can be
formulated in terms of a general relativistic Langevin equation. The vertical oscillations of the disks in the
Schwarzschild and Kerr geometries are considered in detail, and they are analyzed by numerically integrating the
corresponding Langevin equations. The importance of this analysis in the context of explaining the nontrivial
power spectral distribution slopes for Active Galactic Nuclei is discussed.
17 Jan 2012
Probing Planck-Scale Physics with Quantum Optics
Abstract: One of the main challenges in physics today is to merge quantum theory and the theory of general
relativity into a unified framework. Various approaches towards developing such a theory of quantum
gravity are pursued, but the lack of experimental evidence of quantum gravitational effects
thus far is a major hindrance. Yet, the quantization of space-time itself can have experimental
implications: the existence of a minimal length scale is widely expected to result in a modification
of the Heisenberg uncertainty relation. Here we introduce a scheme that allows an experimental
test of this conjecture by probing directly the canonical commutation relation of the center of mass
mode of a massive mechanical oscillator with a mass close to the Planck mass. Our protocol utilizes
quantum optical control and readout of the mechanical system to probe possible deviations from
the quantum commutation relation even at the Planck scale. We show that the scheme is within
reach of current technology. It thus opens a feasible route for tabletop experiments to test possible
quantum gravitational phenomena.
24 Jan 2012
Abstract: Neutron stars are an excellent laboratory for testing matter under
extreme conditions. In particular, a lot of emphasis has been invested
in understanding the interior of neutron stars and the equation of state
of the different possible phases since its direct consequences for the
mass-radius relationship of neutron stars as well as cooling
processes. I will review some results for nucleonic, kaonic and
hyperonic matter together with superfluidity and their consequences for
cooling processes. I will comment on possible constraints not only from
neutron stars observations but also from back-to-Earth experiments, such
as heavy-ion collisions. I will finally outline future prospects to be
tested in neutron stars laboratory.