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Calendar of Physics Talks Vienna
| Asymptotic charges in gravity |
| Speaker: | Mahdi Godazgar (Queen Mary University) |
| Abstract: | I will discuss the Hamiltonian derivation of dual BMS charges at null infinity using the first order formalism. More generally, I will discuss how this idea can be used to classify asymptotic charges in gravity. |
| Date: | Tue, 16.03.2021 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | https://moodle.univie.ac.at/mod/bigbluebuttonbn/guestlink.php?gid=x8o6ILSKJuC9 |
| Contact: | Céline Zwikel |
| Precise strong coupling determinations from tau decays and e+e- to hadrons |
| Speaker: | Diogo Boito (Universidade de São Paulo, currently guest professor at the University of Vienna) |
| Abstract: | We will describe 2 different strategies for the precise extraction of the strong coupling alpha_s,using data for hadronic tau decays and cross sections for e+e- to hadrons.In the first one we determine the strong coupling using finite-energy sum rules combined (i) with a new tau-based vector spectral function and(ii)with a recent compilation of the hadronic R-ratio from available data for e+e- to hadrons below the charm threshold.These determinations are performed at relatively low-energies, with three active flavours(n_f=3).We will also present a new strategy for the determination of the strong coupling with n_f=4 and n_f=5 from ratios of moments of the charm- and bottom-quark vector correlators, which can also be extracted from e^+e^- to hadrons cross sections.I will discuss the perturbative behaviour of these recently introduced moments and their relation to moments employed in . . . |
| Date: | Tue, 16.03.2021 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | https://univienna.zoom.us/j/93104933847?pwd=N0FrL0E1UHlkQWRhQTlQODVkZ3kvUT09 Meeting ID: 931 0493 3847 Passcode: 674625 |
| Contact: | A. Hoang, P. Stoffer |
| On the interface of classical gravity and quantum mechanics |
| Speaker: | Domenico Giulini (Hannover) |
| Abstract: | Testing gravity with genuine quantum systems is on the agenda of many experimental groups worldwide.Such programmes presuppose a well defined scheme according to which the coupling of quantum matter to the classical gravitational field is determined.Such schemes do not exist. Ideally,they should be complete(i.e.account for all terms,say in a given PN-order)and generally applicable(i.e.without a priori restrictions on the quantum states the matter is assuming).But what are the hard principles on which such a scheme can be based? In the first part I will report on some recent work in which the Hamiltonian of an electromagnetically bound 2-particle "atom” in a static Eddington–Robertson parametrised post-Newtonian gravitational field is “derived” to order (1/c)-squared.In the second part will I turn to the Schrödinger-Newton equation as semiclassical model for gravitational self-coupling... |
| Date: | Thu, 18.03.2021 |
| Time: | 15:00 |
| Duration: | 60 min |
| Location: | https://univienna.zoom.us/j/6540036841?pwd=SytyVkZJZzNyRG9lMm13ejlHeHRRUT09 Meeting ID: 654 003 6841 Passcode: Gs4brS |
| Contact: | Piotr Chrusciel, David Fajman |
| Transport in neutron star mergers |
| Speaker: | Alexander Haber (St Louis) |
| Abstract: | With the discovery of gravitational waves from binary neutron star merger, a completely new way to study the QCD phase diagram has become available. In order to learn as much as possible from recent and future detections, detailed simulations combining numerical relativity and hydrodynamics are required. In this talk I try to argue which transport phenomena should be included in future improved simulations, focusing mainly on nuclear and hyperonic bulk viscosity. |
| Date: | Thu, 18.03.2021 |
| Time: | 16:30 |
| Duration: | 60 min |
| Location: | https://tuwien.zoom.us/j/95482849369?pwd=SkU2WU5hMVJBQWsyVlFXRlRvQlIvdz09 |
| Contact: | David Muller, Laura Donnay |
| Silicon nanobeam oscillators for entanglement generation and transduction |
| Speaker: | Johannes Fink (Institute of Science and Technology Austria) |
| Abstract: | We present recent experimental progress with micro-machined silicon nanomechanical oscillators. The interplay between parametric driving, interference and dissipation in a multi-mode cavity electro-optomechanical system can either be used to break time reversal symmetry and act as a compact on-chip microwave circulator [1], to deterministically entangle itinerant microwave modes [2], or to realize bidirectional microwave to telecom wavelength conversion [3]. Observation of stationary entanglement not only reveals the quantum nature of the mechanical oscillator without measuring it directly, it also represents an important resource for quantum communication and quantum enhanced detection protocols.
[1] Mechanical On-Chip Microwave Circulator. S. Barzanjeh, et al., Nat. Commun. 9 (2017)
[2] Stationary Entangled Radiation from Micromechanical Motion. S. Barzanjeh, et al. Nature 570 (2019)
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| Date: | Fri, 19.03.2021 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | on-line |
| Contact: | Jörg Schmiedmayer |
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