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Talks/Seminars



Here you find the upcoming and past talks and colloquia. The colour code and abbreviations:
Seminar of the Institute Quantum Theory Seminar
General Relativity Seminar Seminar of the Helmholtz Institute
Colloquium of the Faculty Other Talks
Seminar of Research Training Group Video seminar of the SFB

HS: Hörsaal (Lecture Hall), SR: Seminarraum (Seminar room), URZ Universitätsrechenzentrum (Computer Center)




Upcoming Talks

Wed, 2016-05-25 16:15
QCD phenomenology and hadron physics from supercomputers
Dr. Andre Sternbeck, TPI Jena
Wed, 2016-06-01 16:15(HS 2, Abbeanum)
Heavy dense QCD from an effective lattice theory
Prof. Owe Philipsen (Uni Frankfurt)
Tue, 2016-06-07 16:15(SR 5, Helmholtzweg 4)
Constraints as evolutionary systems
Prof. Racz

Abstract:
In this talk the constraint equations for smooth spaces satisfying Einstein's equations will be considered. It is shown that, regardless whether the primary space is Riemannian or Lorentzian, the constraints can always be put into the form of an evolutionary system comprised either by a first order symmetric hyperbolic system and a parabolic equation or, alternatively, by a strongly hyperbolic system subsided by an algebraic relation. The (local) existence and uniqueness of solutions to these evolutionary systems is also shown verifying thereby that the proposed evolutionary approach provides a viable alternative to the apparently unique conformal method.
Wed, 2016-06-08 16:15(HS 2, Abbeanum)
Dual Foliation Formulations of General Relativity
or "how I learned to stop worrying and love coordinates"

by Dr. David Hilditch, TPI Jena

Abstract: When solving general relativity numerically for a given physical problem we must use a formulation of the field equations for which the resulting partial differential equation problem is well-posed. Building such a good formulation usually requires making a coordinate choice. This leads to the standard statement that `gauge freedom in general relativity is the choice of coordinates'. The
latter two facts have long bothered me, because one of the first lessons in relativity is that coordinates should in some sense not matter. In my talk I will explain the solution to my earlier confusion. Time permitting I will also describe ongoing work to exploit the solution for practical calculations.


Thu, 2016-06-09 14:15
reserved
reserved
Mon, 2016-06-13 17:15(Hörsaal 1 Abbeanum, Fröbelstieg 1 (PAF Kolloquium))
X, Y, Z - Ein exotisches Hadronen-Alphabet
Prof. Dr. Klaus Peters, GSI Darmstadt
Tue, 2016-06-21 16:15(SR 5, Helmholtzweg 4)
Non-commutative quasicrystals I
Felix Pogorzelski, Technion Haifa, Israel

Abstract:

The investigation of aperiodic point sets originates back to work of Meyer in the 70ies who pursued harmonic analysis on harmonious sets in Euclidean space. Shechtman's discovery of physical quasicrystals (1982) via laser experiments diffraction) triggered a boom of the mathematical analysis of the arising scatter patterns. In recent work with Michael Björklund and Tobias Hartnick, we developed a spherical diffraction theory for cut-and-project sets in general lcsc groups, thus advancing into the non-commutative world. This seminar aims at describing these non-commutative quasicrystals, as well as the dynamical systems which naturally arise from them. We explain further how to use these tools in order to derive the existence and the approximation of the autocorrelation measure.
Mon, 2016-06-27 17:15(Hörsaal 1 Abbeanum, Fröbelstieg 1 (PAF Kolloquium))
Habilitationsvorstellung: Tailoring Light Fields with Silicon Hygens' Metasurfaces
Dr. Isabelle Staude, Abbe Center of Photonics, FSU Jena
Tue, 2016-06-28 16:15(SR 5, Helmholtzweg 4)
Non-commutative quasicrystals II
Felix Pogorzelski, Technion Haifa, Israel

Abstract:

This is a continuation of last week's talk of quasicrystals in possibly non-commutative lcsc groups. We introduce the notion of Gelfand pairs which are a powerful tool to develop a spherical Fourier theory on the spaces we have in mind. The corresponding abstract Fourier transform allows us to define the spherical diffraction measure for non-commutative quasicrystals. Generalizing the classical (abelian) case, we explain why regular cut-and-project sets arising from cocompact lattices amount to pure point diffraction. Joint work with Michael Björklund and Tobias Hartnick.
Wed, 2016-06-29 17:00(Seminarraum HI Jena, Fröbelstieg 3)
TBA
Prof. Thomas Heinzl (Plymouth University)
Fri, 2016-07-01 16:15
TBA
Wed, 2016-07-06 16:15
Numbers and functions in quantum field theory
Dr. Oliver Schnetz, Univ. Erlangen

Quantum field theories describe the fundamental interactions between physical particles. Perturbation theory organizes quantum field theory calculations as expansions in Feynman graphs. Each Feynman graph stands for a multi-dimensional integral over a differential form which is a rational function with integer coefficients. We report on the mathematical structures of the numbers and functions which arise from these integrals. We also indicate how these structures can be used to perform (some) quantum field theory calculations to very high order.
Thu, 2016-07-07 14:15(SR 5, Helmholtzweg 4)
Tetraquarks from Lattice QCD
Prof. Dr. Marc Wagner, Univ. Frankfurt



Calendar

May 2016
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June 2016
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You can also access a full calendar with extended functionality.



Past Talks




Talks from 2016-03-01 up to Today
Mon, 2016-05-23 17:15(Hörsaal 1 Abbeanum, Fröbelstieg 1 (PAF Kolloquium))
tba
Prof. Dr. Christian Eggeling, Univ. of Oxford
Thu, 2016-05-19 14:15(SR 5, Helmholtzweg 4)
Causal Space-time on a Null Lattice
Prof. Dr. Martin Schaden, Rutgers University

Abstract: I propose a discrete model of Quantum Gravity based on the same principle as the Global Positioning System: the intersection of forward light-cones from four spatially separate events (with some restrictions) determines another event. I show that a causal manifold can thus be described by a topologically hypercubic lattice with light-like links; the length of the spatial diagonal of each plaquette being determined by spinors describing the light-like edges. This lattice model has an SL(2,C) x U^4(1) structure group and is geometric. The description foliates in a causal and physically transparent manner. The observables, the most general local action and the integration measure of this model are all determined by this stucture group and for smooth configurations have well-known continuum limits. Consistency constraints on a configuration to describe a causal manifold are derived and a one-parameter ambiguity of the invariant integration measure is exploited to regularize the model. Finally the SL(2,C) structure group is uniquely localized and the integration measure expressed in terms of geometric invariants. Should time and interest permit, I will also discuss global issues and show numerical results on a small lattice describing the vicinity of the Big Bang in the (unphysical) limit where the cosmological term dominates the dynamics.
Tue, 2016-05-17 16:15(SR 5, Helmholtzweg 4)
Quantum gravity aspects of black holes
Prof. Ammon
Fri, 2016-05-13 10:30(SR 5, Helmholtzweg 4)
Duality between higher spin gravity in (Anti-)deSitter spacetime and conformal field theories
Masterverteidigung

Attila Lüttmerding
Thu, 2016-05-12 14:15
Spontaneous breaking of Lorentz symmetry in QED3
Dr. Lukas Janssen (TU Dresden)

Abstract: The phase diagram of quantum electrodynamics in three space-time dimensions as a function of fermion flavor number N exhibits two well-known phases: at large N > Nc1 the system is in a conformal gapless state, while for small N < Nc2 the fermions are expected to develop a dynamical mass due to spontaneous chiral symmetry breaking. Using epsilon expansion near the lower critical dimension of two, in combination with the recent results on the generalization of the F theorem to continuous dimension, we show that Nc1 > Nc2. There is therefore an intermediate range of values of N at which a third phase is stabilized. We demonstrate that this phase is characterized by spontaneous breaking of Lorentz symmetry, in which a composite vector boson field acquires a vacuum expectation value with the fermions and the photon remaining massless.
Wed, 2016-05-11 16:15(HS 2, Abbeanum)
Nonequilibrium entropy production for open quantum systems
Prof. Eric Lutz (FAU Erlangen)

Abstrakt:

Entropy production is a fundamental quantity of nonequilibrium thermodynamics. We here discuss exact microscopic expressions for the nonequilibrium entropy production of closed and open quantum systems that are driven arbitrarily far from equilibrium, in particular beyond the linear response regime. We additionally consider the entropy production rate, which provides information about the speed of nonequilibrium processes, and show that they are bounded from above for quantum systems. The connection with the notion of quantum speed limit is addressed.
Wed, 2016-05-04 14:30
Quasinormal modes in holographic s-wave superconductors
Masterverteidigung

von Johanna Mader
Tue, 2016-05-03 16:15(SR 5, HHW 4)
Hawking Radiation
Prof. Dr. Andreas Wipf, TPI Jena
Mon, 2016-05-02 17:15(Hörsaal 1 Abbeanum, Fröbelstieg 1 (PAF Kolloquium))
Wie entstanden die ersten festen Körper im jungen Sonnensystem?
Prof. Dr. Jürgen Blum, TU Braunschweig
Wed, 2016-04-27 16:15
Nonlinear evolution of perturbed anti-de Sitter spacetime
Dr. Piotr Bizon (Krakow)

Abstract: Dynamics of asymptotically AdS spacetimes is an interesting meeting point of fundamental problems in general relativity, PDE theory, theory of turbulence, and AdS/CFT correspondence. In my talk I will describe recent progress in understanding this problem, focusing on evidence for the instability of AdS spacetime.
Tue, 2016-04-26 17:15(HS 2, Helmholtzweg 5)
Disputation "Untersuchungen von rotierenden und geladenen Staubscheiben mit hochgenauen Näherungslösungen und der Grenzübergang zu Schwarzen Löchern"
Disputation of Martin Breithaupt
Tue, 2016-04-26 14:30(SR 5, Helmholtzweg 4)
Thermodynamics of higher spin black holes
Tim Nitzsche

Masterverteidigung
Thu, 2016-04-21 16:00(Hörsaal 9, Carl-Zeiß-Str. 3)
Magnetic Vortices, vortex lattices and automorphic functions
Prof. Dr. Israel Michael Sigal, Univ. Toronto

Abstract:
I will review recent results concerning the Ginzburg - Landau equations. These equations were first developed to understand macroscopic behaviour of superconductors; later, together with their non-Abelian generalizations - the Yang-Mills-Higgs equations, they became a key part of the standard model in elementary particle physics. They also have found important applications in geometry and topology.

The Ginzburg - Landau equations have remarkable solutions, localized topological solitons, called the magnetic vortices in the superconductivity and the Nielsen-Olesen or Nambu strings in the particle physics, as well as extended ones, magnetic vortex lattices.

I will review the existence and stability theory of the vortex lattice solutions and how they relate to the modified theta functions appearing in number theory and algebraic geometry. Certain automorphic functions play a key role in the theory described in the talk.
Thu, 2016-04-21 14:15(SR 5, Helmholtzweg 4)
Critical scaling in the Large-N O(N) model and its possible connection to quantum gravity
Dr. Péter Mati (Budapest/Szeged)

The critical scaling of the large-N O(N) model in higher dimensions using the exact renormalization group equations will be discussed. Particular attention is paid to the case of d=5 where the scaling exponent of the correlation length has the value 1/3, which coincides with the scaling exponent of quantum gravity in one fewer dimensions. Convincing results show that this relation could be generalized to arbitrary number of dimensions above five. Some aspects of AdS/CFT correspondence will be also discussed.
Wed, 2016-04-20 10:15(HI Jena, Fröbelstieg 3)
QED in the infrared
Dr. Péter Mati (Budapest/Szeged)
Joint Seminar with Helmholtz Institute Jena

Infrared (IR) singularities in massless gauge theories are known since the foundation of quantum field theories. The root of this problem can be tracked back to the very definition of these long-range interacting theories such as QED. The IR catastrophe and its resolution by cancelling the divergences will be discussed. The Bloch-Nordsieck model provides the deep IR description of QED, and in its framework all the radiative corrections to the electron propagator can be fully summed, giving the infra-particle interpretation to the electron. This solution can be obtained by using the functional technique based on the Schwinger-Dyson equation with the aid of the Ward-Takahashi identities. At finite temperatures we use the Keldysh description, that will give a matrix structure to the equation. Again an analytic solution can be obtained for the exact spectral function. The finite temperature solution provides a natural explanation of IR finiteness.
Tue, 2016-04-19 16:15(SR 5, Helmholtzweg 4)
Thermodynamics in GR
Prof. Dr. Gernot Neugebauer, TPI Jena
Mon, 2016-04-11 17:15(Hörsaal 1 Abbeanum, Fröbelstieg 1 (PAF Kolloquium))
Habilitationsvorstellung: Verdrilltes Licht: Physik und Anwendungen
Dr. Marco Ornigotti, Institut für Angewandte Physik, FSU Jena
Thu, 2016-04-07 14:30(SR 5, Helmholtzweg 4)
Verteidigung Masterarbeit
Birger Böning
Mon, 2016-04-04 17:15(HS 1, Abbeanum)
First Observation of Gravitational Waves from a Binary Black Hole Merger
Prof. Dr. Bernd Brügmann, FSU Jena
Fri, 2016-03-11 16:15
Collapse of the Brill waves in a moving-puncture-like gauge (WIP)
Anton Khirnov

Abstract:

One of the open problems in numerical relativity is that of the critical collapse of gravitational waves into a black hole. Quite interestingly, it has been discovered that the supercritical Brill waves, a commonly used family of initial data, cannot be successfully evolved with the moving puncture gauge, popular for black hole simulations. In this talk, we present our work in progress on using a modification of the moving puncture gauge to evolve such data.
Fri, 2016-03-04 16:15(HS 2, Abbeanum)
Verteidigung der Masterarbeit
Anika Dathe