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Calendar of Physics Talks Vienna
| Temperature of Black Holes in Horndeski Gravity Theories |
| Speaker: | Shahin Sheikh Jabbari (IPM) |
| Abstract: | Horndeski theories are the most general family of scalar-tensor gravity with second order equations of motion. In these theories speeds of propagation of gravitons and photons are in general different and gravitons move on an effective metric different than the one seen by photons. These theories admit black hole solutions with the peculiar feature that they do not satisfy the first law with the entropy given by the Wald formula. We argue that the issue with the first law stems from the fact that black hole temperature is not given by the surface gravity of the black hole metric, but with the surface gravity of the effective metric seen by gravitons. The modified temperature, with the entropy unambiguously computed by the solution phase space method, yields the correct first law. We discuss far-reaching implications of our results for black hole thermodynamics beyond Horndeski theories. |
| Date: | Tue, 12.01.2021 |
| Time: | 11:00 |
| Duration: | 60 min |
| Location: | https://moodle.univie.ac.at/mod/bigbluebuttonbn/guestlink.php?gid=x8o6ILSKJuC9 |
| Contact: | Céline Zwikel |
| Speaker: | Antonio Pich (Instituto de Física Corpuscular, Valencia) |
| Abstract: | The experimental data on b → cτν and b → sl+l− transitions exhibit sizeable discrepancies with the Standard Model expectations, suggesting possible violations of lepton universality. We present an overview of the present status and discuss possible interpretations within a model-independent effective Lagrangian approach. We also briefly elaborate on some other claimed flavour anomalies such as the sizeable violation of unitarity that has recently emerged in the first row of the CKM matrix, the large CP asymmetry observed in D0 decays, or the K0 → ππ direct CP- violating ratio εK′ /εK. |
| Date: | Tue, 12.01.2021 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | ZOOM - The link will be provided via email by Simon Plätzer (simon.plaetzer@univie.ac.at) |
| Contact: | A. Hoang, M. Procura, S. Plätzer |
| Measurements of the inelastic cross section of antideuteron, anti-3He and antitriton with the ALICE detector and their implications for dark matter searches |
| Speaker: | Stephan Königstorfer (Fakultät für Physik Technische, Universität München / CERN) |
| Abstract: | The measurement of low-energy cosmic anti-deuterons may reveal the existence of exotic processes such as dark-matter annihilation, since the production rate of these ions through ordinary secondary processes is very low. However, the lack of experimental data at low energies, where both the anti-nuclei production and inelastic cross sections are very poorly known, prevents precise predictions of anti-nuclei fluxes near Earth.
In ultra-relativistic pp, p-Pb and Pb-Pb collisions at the CERN LHC, matter and antimatter are produced in almost equal abundances. This allows us to measure the absorption process of produced (anti-)nuclei in the detector material.
In this talk we present... [for full abstract visit: https://indico.smi.oeaw.ac.at/event/388/] |
| Date: | Wed, 13.01.2021 |
| Time: | 16:30 |
| Duration: | 60 min |
| Location: | Webinar [more details here: https://indico.smi.oeaw.ac.at/event/388/] |
| Contact: | Prof. Dr. Eberhard Widmann, Dr. Martin Simon |
| Static Black Hole Uniqueness For Nonpositive Mass |
| Speaker: | Stefano Borghini (Milano) |
| Abstract: | We discuss the problem of the classification of static vacuum spacetimes with negative cosmological constant. One of the few known results on the subject is a uniqueness theorem for Kottler solutions with nonpositive mass, proved by Lee and Neves through the employment of a Penrose inequality for asymptotically locally hyperbolic manifolds. We will discuss an alternative more elementary proof of this uniqueness result, which has the added benefit of easily generalizing to degenerate horizons. Time permitting, we will then show how similar techniques can be applied in other frameworks, such as in the study of the positive cosmological constant case. |
| Date: | Thu, 14.01.2021 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | https://zoom.us/j/92376135485?pwd=LzlUemhvcU5rL0hhZGxPOUVieDgxZz09 |
| Contact: | Piotr Chrusciel, David Fajman |
| R^2 corrected AdS_2 holography |
| Speaker: | Pedro Aniceto (IST Lisbon) |
| Abstract: | We approach the problem of constructing the holographic dictionary for AdS_2/CFT_1 in the context of higher derivative gravitational actions in AdS_2. We focus on S_2 reductions of four-dimensional N=2 Wilsonian effective actions with Weyl squared interactions restricted to constant scalar backgrounds. BPS black hole near-horizon spacetimes fall into this class of backgrounds and, by identifying the boundary operators dual to the bulk fields, we explicitly show how the Wald entropy of the BPS black hole is holographically encoded in the anomalous transformation of the operator dual to a composite bulk field. Additionally, using a 2d/3d lift, we show that the CFT holographically dual to AdS_2 is naturally embedded in the chiral half of the CFT_2 dual to the AdS_3 spacetime, and we identify the specific CFT_1 operator that encodes the chiral central charge of the CFT_2. |
| Date: | Thu, 14.01.2021 |
| Time: | 16:30 |
| Duration: | 60 min |
| Location: | https://tuwien.zoom.us/j/95482849369?pwd=SkU2WU5hMVJBQWsyVlFXRlRvQlIvdz09 |
| Contact: | Laura Donnay |
| Sub-GeV Scalar Dark Matter - Hints and Probes |
| Speaker: | Jui-Lin KUO (HEPHY, Vienna) |
| Abstract: | Sub-GeV scalar dark matter is motivated by the long-standing INTEGRAL 511 keV line and the muonic g-2 anomaly. In this talk I will focus on its phenomenology at the intensity and precision frontier. An overview of the strategies of different experiments will be given. Together with constraints inferred from direct detection and astrophysics/cosmology, the favoured parameter space to address the aforementioned hints is ruled out.
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| Date: | Fri, 15.01.2021 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | The seminars start at 16:15 but the meetings will be open already at 16:00. The link will be provided via email by Simon Plätzer (simon.plaetzer@univie.ac.at) |
| Contact: | A. Hoang, M. Procura, S. Plätzer |
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