28 Nov 2022
RIND seminar on Mathematical Physics and String Theory
U. Mainz, LMU Munich, U. Heidelberg, U. Vienna 16 Uhr c.t., None |
| Enno Keßler, MPI-M Bonn | |
J-holomorphic curves or pseudoholomorphic curves are maps from Riemann
surfaces to symplectic manifolds satisfying the Cauchy-Riemann equations.
J-holomorphic curves are of great interest because they allow to construct
invariants of symplectic manifolds and those invariants are deeply related to
topological superstring theory. A crucial step towards Gromov–Witten
invariants is the compactification of the moduli space of J-holomorphic curves
via stable maps which was first proposed by Kontsevich and Manin.
In this talk, I want to report on a supergeometric generalization of J-
holomorphic curves and stable maps where the domain is a super Riemann
surface. Super Riemann surfaces have first appeared as generalizations of
Riemann surfaces with anti-commutative variables in superstring theory. Super
J-holomorphic curves couple the equations of classical J-holomorphic curves
with a Dirac equation for spinors and are critical points of the
superconformal action. The compactification of the moduli space of super J-
holomorphic curves via super stable maps might, in the future, lead to a
supergeometric generalization of Gromov-Witten invariants.
Based on arXiv:2010.15634 [math.DG] and arXiv:1911.05607 [math.DG], joint with
Artan Sheshmani and Shing-Tung Yau. | |
| at Zoom | |
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aktuell
29 Nov 2022
Theorie-Palaver
Institut für Physik 14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor) |
| Markus Fröb, U. Leipzig | |
Perturbative Quantum Gravity (pQG), the effective quantum field theory of gravitational fluctuations around a given background, is currently the only experimentally accessible theory of quantum gravity. Its tree-level predictions, in the form of temperature fluctuations of the Cosmic Microwave Background, have been experimentally confirmed, and it is possible that loop corrections are accessible to future experiments. However, while the tree-level results are well understood also from a theoretical point of view, the diffeomorphism symmetry of gravity makes the construction of invariant observables very difficult beyond this. Only recently, this issue has been overcome, and a class of causal invariant observables has been constructed. I will discuss this construction and how it can be related to observations, and present some predictions of pQG for graviton loop corrections to the Newtonian gravitational potential and the Hubble rate, the local expansion rate of the universe. Lastly, I show that pQG also predicts that spacetime becomes non-commutative at the Planck scale, but in a different way from previous approaches. The talk is based (in particular) on the recent papers arXiv:1806.11124, 2108.11960, 2109.09753 and 2207.03345. | |
| at Zoom | |
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Physikalisches Kolloquium
Institut für Kernphysik 16:15 Uhr s.t., HS KPH |
| Prof. Dr. Katrin Amann-Winkel, MPI für Polymerforschung Mainz | |
Water is ubiquitous and the most important liquid for life on earth. Although the water molecule is seemingly simple, various macroscopic properties of water are most anomalous, such as the density maximum at 4°C or the divergence of the heat capacity upon cooling. Computer-simulations suggest that the anomalous behaviour of ambient and supercooled water could be explained by a two state model of water. An important role in this ongoing debate plays the amorphous forms of water. Since the discovery of two distinct amorphous states of ice with different density (high- and low density amorphous ice, HDA and LDA) it has been discussed whether and how this phenomenon of polyamorphism at high pressures is connected to the occurrence of two distinct liquid phases (HDL and LDL). X-ray free electron laser allow us to investigate metastable states of supercooled water within nano- to microseconds. In my talk I will give an overview on our recent X-ray experiments on supercooled water and amorphous ices. | |
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zukünftige Termine
30 Nov 2022
PRISMA+ Colloquium
Institut für Physik 13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7 |
| Prof. Dr. Tetyana Galatyuk, GSI Darmstadt | |
What happens when gold nuclei, accelerated to about 90% of the speed of light, strike gold nuclei at rest? For an extremely short time, t~10^-23 seconds, states of matter at extreme temperatures (10^12 K) and densities (>280 Mt/cm^3) are produced. The microscopic properties of the strong-interaction matter under extreme conditions of temperature and density is a topic of great current interest. Despite 18 orders of magnitude difference in system size and time, the conditions present in heavy-ion collisions share great overlap with the conditions of the strong-interaction matter in neutron-star mergers. The possibility to form and explore in the laboratory strong-interaction matter under extreme conditions is truly fascinating.
The Compressed Baryonic Matter (CBM) experiment at FAIR has the potential to discover the most prominent landmarks of the QCD phase diagram expected to exist at high net baryon densities. The measurement of comprehensive set of diagnostic probes offers the possibility to find signatures of exotic phases, and to discover the conjectured first order deconfinement phase transition and its critical endpoint.
In this talk the referent will focus on relevant observables to study criticality, emissivity, vorticity and equation-of-state of baryon rich matter. Particular emphasis is put on rare probes which are not accessible by other experiments in this energy range. | |
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SPICE-Spin+X Seminar
TUK and JGU 15:00 Uhr s.t., Zoom |
| Alice Mizrahi, CNRS-Thales | |
Multilayer spintronic neural networks with radio-frequency connections | |
| at Zoom and SPICE YouTube Channel | |
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Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)
JGU 10:00 Uhr s.t., TUK, Building 76, Room 276 (LASE) |
| Prof. Victor L’vov, Dept. of Chemical and Biological Physics, Weizmann Institute of Science | |
Hydrodynamic turbulence in superfluid Helium: basic ideas, experiments, and physical models | |
| at Zoom | |
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01 Dec 2022
Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)
JGU 16:15 Uhr s.t., 01-122 Newton Raum |
| Martin Beye, DESY | |
Resonant inleastic X-ray scattering (RIXS) especially in the soft X-ray region has seen a tremendous increase in applicability and scientific insight over the recent years. This was largely enabled by progress in instrumentation and theoretical description. Now the time is ripe to apply RIXS to pressing problems and develop the technique further making full use of the capabilities of novel X-ray sources. In my talk, I will address three main themes from my research:
1. Time-resolved RIXS at free-electron lasers applied to relevant dynamic processes in chemistry (on surfaces, in liquids and in solid catalysts)
2. RIXS with micrometer spatial resolution to resolve domain dynamics in complex materials and on devices in-operando
3. Non-linear spectroscopies in the soft X-ray range to enhance information content and signal levels I will show and discuss experimental results from all research themes and point to future development directions. | |
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