Oberseminar Mathematische Physik
im Wintersemester 2017/2018 von Prof. Dr. D. Dürr, Prof. Dr. P. Pickl und
Dirk  André Deckert
The seminar is usually on Wednesdays, 16:15h, in room B004.
Talks
Date 
Room 
Title 
Speaker 

Wed 18.10.17, 16:15 
B004 
The Method of Epstein and Glaser applied to external field QED, part 2 
Markus Nöth 
Wed 25.10.17, 16:15 
B004 
Defense: Arrival Time Distributions of spin1/2 Particles 
Siddhant Das 
Wed 01.11.17, 16:15 
B004 
No seminar  Allerheiligen 
 
Wed 08.11.17, 16:15 
B004 
Propagation of chaos in the VlasovPoisson system 
Philipp Grass 
Wed 15.11.17, 16:15 
B004 
Bose Einstein Condensation in attractive systems 
Maximilian Jeblick 
Wed 22.11.17, 16:15 
B004 
Interior boundary conditions for multitime wave functions, or: Creating and annihilating Dirac particles in 1D without infinities 
Lukas Nickel 
Wed 29.11.17, 16:15 
B004 
Mathematical Foundations of the Statistical Analysis in Physics 
Paula Reichert 
Wed 06.12.17, 16:15 
B004 
GhirardiRiminiWeber model with massive flashes
I will introduce a modification of the GhirardiRiminiWeber (GRW) model in which the flashes (or collapse spacetime events) source a classical gravitational field. The resulting semiclassical theory of Newtonian gravity preserves the statistical interpretation of quantum states of matter in contrast with mean field approaches. It can be seen as a discrete version of recent proposals of consistent hybrid quantum classical theories. The model is in agreement with known experimental data and introduces new falsifiable predictions: (1) particles do not attract themselves, (2) the 1/r gravitational potential of Newtonian gravity is cutoff at short (. 10−7m) distances, and (3) gravity makes spatial superpositions decohere at a rate inversely proportional to that coming from the vanilla GRW model. Together, the last two predictions make the model experimentally falsifiable for all values of its parameters. 
Antoine Tilloy 
Wed 13.12.17, 16:15 
B004 
CANCELLED! Guest cannot come due to bad weather 
 
Wed 20.12.17, 16:30 
B448 
End of the year session
In absence of a speaker, we will consider a celebratory model for prechristmas dynamics of many interacting group members. The effect of cookies and the consumption of warm liquids on the social behaviour of mathematicians will be empirically tested. All group members are invited! 
 
Wed 10.01.18, 16:15 
B004 
How electrons spin
There are a number of reasons to think that the electron cannot truly be spinning. Given how small the electron is generally taken to be, it would have to rotate superluminally to have the right angular momentum and magnetic moment. Also, the electron’s gyromagnetic ratio is twice the value one would expect for an ordinary classical rotating charged body. These obstacles can be overcome by examining the flow of mass and charge in the Dirac field (which gives the classical state of the electron). Superluminal velocities are avoided because the electron’s mass and charge are spread over sufficiently large distances that neither the velocity of mass flow nor the velocity of charge flow need to exceed the speed of light. The electron’s gyromagnetic ratio is twice the expected value because its charge rotates twice as fast as its mass. 
Charles "Chip" Sebens 
Wed 17.01.18, 16:15 
B004 
Asymptotic completeness in dissipative scattering theory 
Jérémy Faupin 
Wed 24.01.18, 16:15 
B004 
The attoclock and the tunneling time problem
The tunnelling time problem is almost as old as quantum mechanics itself and is a highly debated subject. Within "conventional" quantum mechanics, many conflicting theories have been developed over the decades. Here we review some of those definitions, namely the ButtikerLandauer, PollakMiller, EisenbudWigner, and Larmor times. While based on very different physical arguments, all of these definitions can be presented as averages using the tunneling time probability amplitudes constructed with the Feynman path integral (FPI) approach. In addition, I show how the FPI approach can be used to calculate tunneling time probability amplitudes. Bohmian mechanics, offers an alternative definition, namely Bohmian time. We show how this time can be calculated as well in the context of tunnel ionization and what it might mean. All of these theoretical tunneling times are discussed in the context of the attoclock experimental measurements and compared to the experimentally defined "attoclock tunneling time".

Alexandra Landsman 
Thu 25.01.18, 16 Uhr 
B133 
Symplectization of Vlasov dynamics and
application to the VlasovPoisson system
Vlasov equations are nonlinear transport equations that describe selfconsistent dynamics of densities in various physical systems. They arise as the continuum limit of many particle point mass systems with specified interaction laws. For example, VlasovPoisson is the limit equation of the classical Newtonian many body problem.
Although the equations are the continuum limit of Hamiltonian systems, Hamiltonian structure has not yet been described in a manner fruitful from the PDE side. In the first part, we derive a simple Hamiltonian structure for general Vlasov systems, that was firstly noted by Fröhlich, Knowles, and Schwarz for the example of nonrelativistic twobody interaction systems. In the second part, we sketch the proof of wellposedness for the Hamiltonian equations of the VlasovPoisson problem. At last, we shortly discuss open problems related to the equation, such as periodic solutions and mean field limit. 
Robert Neiss 
Wed 31.01.18, 16:15 
B004 
Interacting particles in R^d at low temperatures: towards phase
transitions and metastability
Phase transitions for lattice systems such as the Ising
model are wellunderstood. For particles in R^d, the situation is much
less satisfying and the existence of phase transitions has been proven
only for some models, notably the WidomRowlinson model and Kac
interactions (Lebowitz, Mazel, Presutti) model. I will present some
results on the lowtemperature behavior of classical Gibbs measures
motivated by the search for phase transitions, and for a concrete
model sketch some results on continuum Glauber dynamics at low
temperature in finite volume, specifically Arrhenius law and
nucleation barriers. Based on work with F. den Hollander, W. König, B.
Metzger. 
Sabine Jansen 
Wed 07.02.18, 16:15 
B004 
CANCELLED due to illness!

Stefan Adams 
Organisation of the Oberseminar:
Lukas Nickel. Just write me an email with any questions or requests or if you would like to present.
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