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Calendar of Physics Talks Vienna
| Speaker: | Iva Lovrekovic (Imperial College London) |
| Abstract: | I will talk about the two-vierbein gravity theory that is obtained from the conformal group gauge theory. The well known gauge theory of conformal group is conformal gravity, however if we weaken the constraint on the gauge generator of translations, the obtained theory differs. Starting with the action from which one can derive Einstein gravity and conformal gravity upon imposing suitable constraints, we keep two independent gauge fields and integrate out the field corresponding to the generator of Lorentz transformations. We keep two gauge fields and consider the perturbation around the AdS space. We obtain two linearised equations that differ from both, Einstein gravity and conformal gravity linearised equations. We also consider two examples: a possible redefinition of the second gauge field; and the perturbation around the flat space. |
| Date: | Tue, 04.06.2019 |
| Time: | 13:45 |
| Duration: | 60 min |
| Location: | TU Wien, Wiedner Hauptstraße 8, Yellow Area, 9th floor, Seminar Room DB 09 E23 |
| Contact: | S. Fredenhagen, D. Grumiller |
| Liquid/Vapor Interfaces Investigated with Photoelectron Spectroscopy |
| Speaker: | Hendrik Bluhm (Fritz Haber Institute of the Max Planck Society, Department of Inorganic Chemistry, Berlin/Germany) |
| Abstract: |
Aqueous solution/vapor interfaces govern important phenomena in the environment and atmosphere, including the uptake and release of trace gases by aerosols and CO2 sequestration by the oceans.[1] A detailed understanding of these processes requires the investigation of liquid/vapor interfaces with chemical sensitivity and interface specificity under ambient conditions, i.e., temperatures above 200 K and water vapor pressures in the millibar to tens of millibar pressure range. This talk will discuss opportunities and challenges for investigations of liquid/vapor interfaces using X-ray photoelectron spectroscopy and describe some recent experiments that have focused on the propensity of certain ions and the role of surfactants at the liquid/vapor interface.
[1] O. Björneholm et al., Chem. Rev. 116, 7698 (2016)
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| Date: | Tue, 04.06.2019 |
| Time: | 16:00 |
| Location: | TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner Hauptstraße 8-10 Yellow Tower „B“, 5th floor, SEM.R. DB gelb 05 B |
| Contact: | Univ.Prof. Dr. Ulrike Diebold |
| Nucleon-antinucleon annihilation at low energy |
| Speaker: | Prof. Claude Amsler (CERN and SMI) |
| Abstract: | A comprehensive study of the annihilation process, that occurs when a low energy antiproton (pbar) stops in matter, was performed between 1983 and 1996 at LEAR of CERN. Some of the experimental data on pbar and nbar annihilation will be reviewed, with emphasis on pbar-p annihilation at rest in hydrogen. The annihilation mechanism is still not understood in detail, due to the complexity of the short range strong force, the multiparticle interaction and the presumed roles of quarks and gluons. However, global features such as final state multiplicities and energy distributions can be reproduced reasonably well. Several exotic reactions leading to hadrons containing strange quarks, and unusual annihilations involving more than one nucleon (Pontecorvo reactions), have been studied, which may shed light on the annihilation process, on the roles of quarks and on the structure of the nucleon. |
| Date: | Wed, 05.06.2019 |
| 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 |
| The wave equation near flat Friedmann-Lemaître-Robertson-Walker and Kasner Big Bang singularities |
| Speaker: | Anne Franzen (Lisbon) |
| Abstract: | We consider the wave equation, $\square_g\psi=0$, in fixed flat
Friedmann-Lemaître-Robertson-Walker and Kasner spacetimes with topology
$\mathbb{R}_+\times\mathbb{T}^3$. We obtain generic blow up results for
solutions to the wave equation towards the Big Bang singularity in both backgrounds.
In particular, we characterize open sets of initial data prescribed at a spacelike hypersurface close to the singularity, which give rise to solutions that blow up in an open set of the Big Bang hypersurface $\{t=0\}$. The initial data sets are characterized by the condition that the Neumann data should dominate, in an appropriate $L^2$-sense, up to two spatial derivatives of the Dirichlet data. For these initial configurations, the $L^2(\mathbb{T}^3)$ norms of the solutions blow up towards the Big Bang hypersurfaces of FLRW and Kasner with inverse polynomial and logarithmic rates respectively. |
| Date: | Thu, 06.06.2019 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Seminarraum A, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel, D. Fajman |
| Consistent truncation and de Sitter space from gravitational instantons |
| Speaker: | Dimitrios Tsimpis (Université Claude Bernard Lyon 1) |
| Abstract: | I will discuss a recently constructed four-dimensional consistent truncation to the bosonic part of the universal sector of Calabi-Yau IIA compactification, in the presence of background flux and fermionic condensates generated by gravitational instantons. The condensates are controlled by the ratio of the characteristic length of the Calabi-Yau to the string length, and can be fine-tuned to be dominant in a region of large volume and small string coupling. The consistent truncation admits de Sitter solutions supported by the condensates, subject to certain validity conditions that I will discuss. Based on arXiv:1903.10504 |
| Date: | Thu, 06.06.2019 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | Institute for Theoretical Physics, TU Wien, Seminar room 10th floor (yellow area), Wiedner Haupstr. 8-10, 1040 |
| Contact: | Timm Wrase |
| High Precision Mass Measurements of Nuclei and the Neutron Star Merger |
| Speaker: | Prof. Ani Aprahamian (A. Alikhanyan National Laboratory of Armenia and Institute of Structure & Nuclear Astrophysics University of Notre Dame, Indiana, USA) |
| Abstract: | The US science academies report on “Connecting Quarks to the Cosmos'' identified eleven of the most challenging open questions for all of physics in the 21st century. One of these eleven questions included the identification of the site(s) for the production of the heaviest elements found in nature: How were elements Fe to U made?
Most of the elements above Fe in the periodic table are thought to have been produced by either the slow (s-process) or rapid (r-process) capture of neutrons in astrophysical environments. The s-process proceeds close to stability and astrophysical sites have been identified, while the r-process allows the production of nuclei much further from stability and potential sites remain mostly unresolved.
The recent observation of gravitational waves from two neutron star mergers simultaneously with the... [full abstract here https://indico.smi.oeaw.ac.at/event/331/] |
| Date: | Thu, 06.06.2019 |
| Time: | 16:30 |
| Duration: | 60 min |
| Location: | Währinger Str. 17, 1090 Wien (Kavalierstrakt, 1. Stock, Victor-Franz-Hess Hörsaal) |
| Contact: | Prof. W. Kutschera, Prof. E. Widmann, Prof. E.M. Wild |
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