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Calendar of Physics Talks Vienna
| Probing the asymptotic structure of 4d Einstein gravity: flat from AdS |
| Speaker: | Matthieu Vilatte (Ecole Polytechnique, Paris & Aristotle University of Thessaloniki) |
| Abstract: | My talk will focus on the structure of gravity at large distances and especially on how one can get insights on the asymptotically flat structure from the one of Anti-de Sitter spacetimes. I will start by recalling some basics on the gauge fixing approach to the IR structure of gravity, insisting on the fundamental examples of the Fefferman-Graham and Bondi gauges and on asymptotically AdS and flat spacetimes. As Ricci flat solutions are usually obtained from a the \Lambda -> 0 limit of Einsteinâs spacetimes, I will describe how one can get the flat solution space and flux/balance equations from a careful Laurent expansion of the AdS energy-momentum tensor and the requirement of the line-element finiteness, the analysis being conducted in a covariant version of the Newman-Unti gauge that will be presented prior to these developments. |
| Date: | Tue, 16.01.2024 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Erwin Schroedinger-Hoersaal (Boltzmanngasse 5, 5th floor) |
| Contact: | Adrien Fiorucci, Daniel Grumiller |
| Revisiting strong-coupling determinations from event shapes |
| Speaker: | Guido Bell (University of Siegen) |
| Abstract: | Electron-positron event shapes are among the oldest and most established observables for extracting the strong coupling constant.
The most precise determinations based on the thrust and C-parameter distributions yielded values, however, that are currently in tension with the PDG world average.
We therefore revisited the theoretical foundation of the event-shape fits, in particular their implementation of non-perturbative effects.
Interestingly, we found that the combined effect of altering the renormalon subtraction scheme and perturbative scale parameters can lead
to a few-percent-level impacts on the extracted alpha_s value, indicating a potentially important systematic theory uncertainty that should be accounted for. |
| Date: | Tue, 16.01.2024 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Fakultaet fuer Physik, Erwin-Schroedinger-HS, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, M. Procura |
| Conformal Carrollian scalars and their holographic realisations |
| Speaker: | Simon Pekar (Ecole Polytechnique) |
| Abstract: | Motivated by the extension of the AdS/CFT correspondence to asymptotically flat space-times and in particular the Carrollian approach to flat-space holography, I will present a holographic realisation of conformal (massless) Carrollian scalar field theories, seen as boundary degrees of freedom living on the null infinity of Minkowski space-time. I will present both the electric and magnetic theories, with a particular emphasis on their symmetries. This analysis may serve as a first step towards establishing a holographic dictionary, and I will argue that both theories are crucial in the study of flat-space higher-spin holography. |
| Date: | Thu, 18.01.2024 |
| Time: | 17:00 |
| Duration: | 60 min |
| Location: | TU Wien, Freihaus, Seminar room 10th floor |
| Contact: | Iva Lovrekovic, Adrien Fiorucci |
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