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Calendar of Physics Talks Vienna
| The Λ-BMS4 group of dS4 and new boundary conditions for AdS4 |
| Speaker: | Romain Ruzziconi (Université Libre de Bruxelles) |
| Abstract: | In this talk, I will discuss the solution space of general relativity in Bondi gauge, with non-vanishing cosmological constant. Using the dictionary between Bondi and Fefferman-Graham gauges, the analogues of the Bondi news, Bondi mass and Bondi angular momentum aspects at the boundary of generic asymptotically locally dS4 spacetimes will be identified. Then, I will introduce the Λ-BMS4 group as the residual symmetry group of Bondi gauge after boundary gauge fixing. This group consists in infinite dimensional non-abelian supertranslations and superrotations and it reduces in the asymptotically flat limit to the extended BMS4 group. Furthermore, I will present new boundary conditions for asymptotically locally AdS4 spacetimes which admit R times the group of area-preserving diffeomorphisms as the asymptotic symmetry group. |
| Date: | Tue, 12.11.2019 |
| Time: | 13:45 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | S. Fredenhagen, D. Grumiller |
| Simulating the earliest stages of heavy-ion collisions |
| Speaker: | Andreas Ipp (TU Wien) |
| Abstract: | The quark-gluon plasma is a state of matter which can be created at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC). The initial stage right after the collision of two heavy nuclei at sufficient energies is dominated by strongly anisotropic gluonic fields and is known as Glasma.
In this talk, I present our three-dimensional simulations of the Glasma stage. The formalism is based on the color glass condensate framework using a colored particle-in-cell method. By incorporating nuclei with finite thickness along the beam axis, we naturally break boost invariance and obtain Gaussian-like rapidity profiles of energy densities which agree well with experimental data. The applicability of our simulations is limited by the numerical Cherenkov instability. By constructing a new lattice action, we can cure this instability along one lattice direction. |
| Date: | Tue, 12.11.2019 |
| Time: | 16:15 |
| Location: | Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, S. Plätzer |
| Ion beam spectroscopy with 2D materials - Towards timing information in ion-solid scattering |
| Speaker: | Dr. Richard Wilhelm (TU Wien, Institute of Applied Physics) |
| Abstract: | The interaction of slow ions with atoms, molecules, and solids is characterized by a plethora of different phenomena. Electrons are captured and re-ionized, the ion scatters on target nuclei and sets them into motion. On surfaces many moving target atoms are forming a collisional cascade which may cause permanent material damage. In experiment we have only access to the final outcome of an ion impact and measure emitted photons, electrons, and sputtered surface atoms, which are the end result of the entire interaction sequence. Also material property alterations due to ion beam irradiation can be analyzed by microscopy or surface sensitive spectroscopy methods. At the moment, we are not able to resolve the different interaction steps from one another in the time-domain in order to study their individual features ... [full abstract: https://indico.smi.oeaw.ac.at/event/353/] |
| Date: | Wed, 13.11.2019 |
| Time: | 17:00 |
| Duration: | 60 min |
| Location: | Stefan-Meyer-Institut, Boltzmanngasse 3, 1090 Wien, Seminarraum 3-2-08 (2. Stock) |
| Contact: | Prof. Dr. Eberhard Widmann, Dr. Martin Simon |
| Standing gravitational waves |
| Speaker: | Sebastian Szybka (Cracow) |
| Abstract: | im Rahmen des Literaturseminars der Gravitationsphysik:
I will propose a covariant definition of standing gravitational waves. |
| Date: | Thu, 14.11.2019 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel, D. Fajman |
| Speaker: | Jan Novák (Technical University of Liberec) |
| Abstract: | One of the quickly developing mathematical disciplines is algebraic geometry. We will study plabic (planar bicolored) graphs. We define LE-diagrams and decorated permutations and we mention that these three notions are interconnected. We further introduce winding index and formal boundary measurements. The Amplituhedron A_{n,k,m} is the image in the Grassmannian Gr_{k(k+m)} of the totally nonnegative part of Gr_{k,n} under a linear map. It was introduced in 2013 in order to give a geometric basis for the computation in physics. We show a completely different possible usage of plabic graphs in quantum gravity, which is a work in progress. |
| Date: | Thu, 14.11.2019 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | TU Wien, Wiedner Hauptstraße 10, Yellow Area, Seminar Room |
| Contact: | D. Grumiller, C. Zwikel |
| Dense quark and nuclear matter from holography |
| Speaker: | Andreas Schmitt (University of Southampton) |
| Abstract: | Neutron stars host the densest matter in the universe and possibly contain a core of deconfined quark matter. Therefore, a theoretical understanding of these ultra-dense objects requires an approach that accounts for both nuclear and quark matter on the same footing and for a possible transition between them. I will present a holographic calculation where nucleons are described by interacting instantons and will show how nuclear matter can be continuously connected with deconfined quark matter. |
| Date: | Fri, 15.11.2019 |
| Time: | 11:00 |
| Duration: | 60 min |
| Location: | Institute for Theoretical Physics, TU Wien, Seminar room 10th floor (yellow area), Wiedner Haupstr. 8-10, 1040 |
| Contact: | Anton Rebhan |
| Phases in two flavour holographic QCD |
| Speaker: | Varun Sethi (University of Delhi) |
| Abstract: | The Witten-Sakai-Sugimoto model is used to study two flavour Yang-Mills theory with large number of
colours at finite temperature and in presence of chemical potential for baryon number and isospin. |
| Date: | Fri, 15.11.2019 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Institute for Theoretical Physics, TU Wien, Seminar room 10th floor (yellow area), Wiedner Haupstr. 8-10, 1040 |
| Contact: | Anton Rebhan |
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