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Calendar of Physics Talks Vienna
| New symmetries for general relativity |
| Speaker: | Simone Speziale (Marseille, CPT) |
| Abstract: | In the last few years there has been a lot of interest in asymptotic
symmetries in gauge theories and general relativity, in relation with
deep infrared physics and memory effects. I will first give a brief
pedagogical introduction showing how the surface charges associated
with asymptotic symmetries follow from a standard application of
Noether's theorem, and then discuss three extensions of the BMS
symmetries that have been proposed in the context of general
relativity, with their motivations. Among the new results, an
algebraic perspective on
the flux-balance laws of gravitational waves,
a proposed modification of the Barnich-Troessaert bracket for the charges,
and the possibility of discriminating bulk-equivalent descriptions of
gravity such as
metric and tetrad formulations, with some speculative implications for
quantum gravity. |
| Date: | Tue, 15.03.2022 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Sem.R. DA, gruen 05 (TU Wien, Freihaus) |
| Contact: | D. Grumiller, S. Fredenhagen, E. Battista, R. Ruzziconi |
| Integrating out heavy fields in the path integral using the background-field method |
| Speaker: | Maximilian Stahlhofen (Freiburg University) |
| Abstract: | I will describe a state-of-the-art functional integration approach to integrate out heavy fields of beyond Standard Model (BSM) theories at one-loop level.
The operators of the resulting effective field theory (EFT) encode the effects of the heavy loops in their Wilson coefficients.
The method is based on the background-field formalism and the expansion by regions.
As an illustrative example I will discuss the matching of a singlet extension of the Standard Model onto the Standard Model EFT (SMEFT).
I will particularly focus on issues related to the mixing of Higgs fields in the BSM model.
In this context a proper scheme choice for the renormalization of tad poles and mixing angles turns out to be crucial.
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| Date: | Tue, 15.03.2022 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | Erwin-Schrödinger-HS, Fakultät für Physik, Boltzmanngasse 5, 5. Stock sowie ZOOM https://univienna.zoom.us/j/93427906843?pwd=YjhSejdUVW16QjVQYUh5TVNSNFNhQT09 |
| Contact: | A. Hoang, M. Procura |
| Spectral characterization of a type-0 entangled photon-pair source at telecom wavelengths |
| Speaker: | Mirela Selimovic (Austrian Academy of Sciences, Vienna, Austria) |
| Abstract: | In quantum communication, entangled photon-pair sources are, among other applications, an indispensable resource for the realization of quantum key distribution protocols. In theory, these protocols promise unconditionally secure communication based on the laws of quantum physics. For the practical implementation of entanglement-based protocols, a reliable source of entangled photon pairs is required. Entangled photon-pair sources are realized by a setup of optical components with wavelength dependencies. The present work investigates the spectral bandwidth of two entangled photon-pair sources that exploit spontaneous parametric down-conversion (SPDC) inside a nonlinear magnesium oxide doped periodically poled lithium niobate crystal. The SPDC process has a low probability to convert a single high-frequency pump photon to an entangled photon pair of lower frequency. The entangled photon- |
| Date: | Wed, 16.03.2022 |
| Time: | 11:00 |
| Duration: | 45 min |
| Location: | Seminarraum ATI |
| Contact: | Julian Leonard |
| Gravitational instantons and special geometry |
| Speaker: | Lars Andersson (Albert Einstein Institut, Golm) |
| Abstract: | Gravitational instantons are Ricci flat complete Riemannian 4-manifolds with at least quadratic curvature decay.
In this talk I will introduce some notions of special geometry, discuss known examples, and mention some open questions.
The Chen-Teo gravitational instanton is an asymptotically flat, toric, Ricci flat family of metrics on $\mathrm{CP}^2 \setminus \mathrm{S}^1$,
that provides a counterexample to the classical Euclidean Black Hole Uniqueness conjecture. I will sketch a proof that the Chen-Teo Instanton is Hermitian and non-Kähler.
Thus, all known examples of gravitational instantons are Hermitian. This talks is based on joint work with Steffen Aksteiner, cf. https://arxiv.org/abs/2112.11863. |
| Date: | Thu, 17.03.2022 |
| Time: | 15:00 |
| Duration: | 60 min |
| Location: | ZOOM https://univienna.zoom.us/j/6540036841?pwd=SytyVkZJZzNyRG9lMm13ejlHeHRRUT09 Meeting ID: 654 003 6841 Passcode: Gs4brS |
| Contact: | P. Chrusciel, D. Fajman |
| Stringtheorie und die Geometrisierung der Quantenphysik |
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