Vienna Theory Lunch Seminar
by Iva Lovrekovic (VUT),
Max Riegler (VUT), Jakob Salzer (VUT),
Vienna University of Technology
(VUT): Wiedner Hauptstr. 8-10, yellow area,
10th floor, seminar
University of Vienna (UV):
Boltzmanngasse 5, 5th floor, Schrödinger
Lecture Hall / large seminar
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) gratis zur Verfügung gestellt.
a lunch seminar as
The focus is
on recent theoretical
by Master students,
students but should
also be comprehensible
attend so that
an overview of
Speakers are also encouraged
on their motivation
In order to avoid any "loss of time" we provide a free lunch (pizza).
Wie kann ich teilnehmen?
How can I join?
erscheinen! Um per Email informiert zu werden, bitte in die
Mailinglist eintragen oder Mail an
via email go
drop an email to
Mar 4 2014
Can time be saved in quantum cosmology?
I will discuss the problem of time in quantum cosmology and
present a possible time evolution for Minisuperspaces.
Mar 11 2014
Holographic zero sound at finite
I will discuss some recent work concerning the existence and
properties of zero sound in the Sakai-Sugimoto model at
Mar 18 2014
Upgrade of the Global Muon Trigger for the CMS Experiment at the LHC
The Level-1 Trigger for the Compact Muon Solenoid (CMS)
experiment with an emphasis on the Global Muon Trigger
(GMT). I will then detail the planned upgrades to this
system for the Large Hadron Collider (LHC) run period
beginning in 2015. Finally I will introduce one of the
analyses that could significantly benefit from this upgrade.
Mar 25 2014
Conformal gravity holography in four dimensions
Abstract: We formulate four-dimensional conformal gravity with (Anti-)de Sitter boundary conditions that are weaker than Starobinsky boundary conditions, allowing for an asymptotically subleading Rindler term concurrent with a recent model for gravity at large distances. We prove the consistency of the variational principle and derive the holographic response functions. One of them is the conformal gravity version of the Brown-York stress tensor, the other is a `partially massless response'. The on-shell action and response functions are finite and do not require holographic renormalization. Finally, we discuss phenomenologically interesting examples, including the most general spherically symmetric solutions and rotating black hole solutions with partially massless hair.
Apr 1 2014
Analogies between Soft Matter Systems and Manner Schnitten
colloids are a model system introduced to model anisotropic
interactions in colloidal dispersion. After a brief
introduction on the
topic, we introduce Inverse Patchy Colloids, and show our
study of the
phase diagram, which reveals structures similar to the
Apr 8 2014
Holography of the chiral magnetic effect and anisotropy in heavy ion collisions
The chiral magnetic effect (CME) is a highly discussed
effect in heavy-ion collisions stating that, in the presence
of a magnetic field B, an electric current is generated in
the background of topologically nontrivial gluon fields. We
present a holographic (AdS/CFT) description of the CME in
terms of a fluid-gravity model which is dual to a
strongly-coupled plasma with multiple anomalous U(1)
currents. In the case of two U(1) charges, one axial and one
vector, the CME formally appears as a first-order transport
coefficient in the vector current. We will holographically
compute this coefficient at strong coupling and compare it
with the hydrodynamic result. Finally, we will discuss an
anisotropic variant of the model and study a possible
dependence of the CME on the elliptic flow coefficient v_2.
Apr 15 2014
The non relativistic superparticle
Abstract: I will give a short introduction to supersymmetry and explain what we understand by non-relativistic supersymmetry. This will lead to a notion of non-relativistic supergravity which I will use to construct the action of a (super) point-particle. Finally, I will discuss different gaugings of this action to describe a point-particle in backgrounds with different symmetries; from the Galilean point-particle to the Newton--Cartan point-particle.
Apr 22 2014
Apr 29 2014
Using brilliant X-ray sources to uncover atomic-scale migration models -- an introduction to aXPCS
Abstract: Advances of Synchrotron sources in the last two decades made it possible to expand Dynamic Light Scattering to the X-ray regime. In recent years our group explored the limits of this technique by using it to study diffusion on the atomic scale. This talk will give an introduction to atomic-scale X-ray Photon Correlation Spectroscopy and discuss how coherent X-rays can give a picture of reals space circumventing the phase problem. Selected diffusion mechanisms will be exemplified and compared with experimental data.
May 6 2014
Why three is close to infinity and two is much greater than one
Abstract: In condensed matter systems with strong electronic correlations, the familiar picture of a non-interacting electron cloud breaks down. These materials show facinating "emergent" phenomena. However, the breakthrough in treating many of such systems numerically only came in the 1990s with the advent of dynamical mean field theory (DMFT)  and related in ab-initio approaches like LDA+DMFT .
May 13 2014
Variable flavor number schemes in QCD
Abstract: In this talk I will illustrate how to include heavy quark effects in QCD processes with various dynamical scales. The resulting mass factorization theorems resum all large logarithms and can account for arbitrary hierarchies between the mass scale and the kinematic scales. Specific examples covered are the hadronic R-ratio, deep-inelastic scattering and event shapes.
Materials with strong electronic correlations: The LDA+DMFT approach
Abstract: Calculating electronic properties of materials is an important task in solid state theory. A powerful tool to perform electronic structure calculations is density functional theory in its local density approximation (LDA). However, LDA fails if electronic correlations are strong. On the other hand, the dynamical mean field theory (DMFT) can deal with strongly correlated model Hamiltonians. In this talk I will explain how LDA and DMFT can be combined in order to perform realistic calculations for strongly correlated materials and I will show some preliminary results for the materials I am currently working on.
May 27 2014
qBounce: Frequency's view on Newton's Inverse Square Law of Gravity
Abstract: In the frame of the qBounce experiment, resonant transitions between several of the lowest quantum states of gravitationally bound neutrons are observed for the first time. The coupling between the states is provided by well-defined mechanical oscillations of neutron mirrors. The presented spectroscopy method enables a frequency's view on Newton's Inverse Square Law of Gravity, which has been put under scrutiny by theoretical extensions of the Standard Model. As yet undiscovered particles of dark matter or dark energy would introduce a measurable energy shift, we can present experimental limits for dark-energy chameleons fields and the pseudo-scalar interaction of an axion, a prominent dark matter particle.
June 3 2014
One Symmetry to Rule Them All
Abstract: I outline the various apparently different problems which can be dealt with the symmetries of the Galilean Conformal Algebra. These include applications to flat holography, non-relativistic physics and the tensionless limit of string theory.
June 10 2014
Periodic Boundary Conditions and their Effects on the Simulation of Drops
Abstract: The use of periodic boundary conditions is a common trick used when doing molecular simulations on the computer. After a short introduction of this technique, we look at the effect it has on the simulation of droplets in a simulation box which is the emergence of so called geometric phases that are characterized by droplet shapes other than spherical. Transitions between these phases have been observed to be responsible for exponential slowing down in simulations and hence we will try characterize them by finding a suitable order parameter.
June 17 2014
Violation of Lorentz invariance, related phenomena, and experiments
Abstract: In the past 15 years the search for a possible violation of Lorentz invariance has become one pillar in fundamental research. This talk will give an introduction to this hot and fascinating topic. First of all it will be motivated why Lorentz symmetry may be violated in the vicinity of the Planck scale. As a next step an effective framework, which describes Lorentz violation for energies much smaller than the Planck scale, shall be introduced. The latter is known as the Standard-Model Extension whose Lagrange density includes all terms consistent with the ordinary Standard Model (plus gravity) but violating Lorentz invariance. This will lead us to possible phenomena that occur in this context such as vacuum birefringence. The last part of the talk will be dedicated to examples for experiments that are used to search for Lorentz violation in nature.
June 24 2014
Solving the time-dependent many-body problem without wavefunctions
Abstract: The theoretical description of correlated quantum many-body systems is one of the major challenges in current physics. Quantum correlations occur at practically all levels of complexity: from multi-photon ionization of atoms to high temperature superconductivity in solids. In general, the amount of information stored in the wavefunction makes it inaccessible to analytical or even numerical calculations. However, many dynamical observables including the energy are completely defined by the reduced two-particle density matrix. Recently a method has been developed to calculate the ground state energy of complex molecules based on the two-particle density matrix without knowledge of the full wavefunction. In this talk i will present a time-dependent version of this theory. As a testing ground we use the lithium hydrate molecule in high intense laser fields. The accuracy of the newly developed theory is benchmarked against the multiconfigurational time-dependent Hartree-Fock method.