CPT

Calendar of Physics Talks Vienna

Digging traversable wormholes
Speaker:Roberto Emparan (Barcelona U.)
Abstract:In recent years there have appeared several constructions of traversable wormholes, in four and other dimensions, which only involve physically acceptable, controllable ingredients. They connect in deep ways many aspects of gravity, quantum field theory, and quantum information. I will discuss several features of these constructions, with a focus on traversability, connectivity between multiple mouths, and the (im)possibility of time travel.
Date: Tue, 27.04.2021
Time: 14:00
Duration: 60 min
Location:https://moodle.univie.ac.at/mod/bigbluebuttonbn/guestlink.php?gid=x8o6ILSKJuC9
Contact:Céline Zwikel

Covariant Weyl calculus with application to geometrical optics in relativity
Speaker: Jérémie Joudioux (AEI Golm)
Abstract:Geometrical optics consists of approximating the evolution of an electromagnetic wave,solution to Maxwell’s equations,by ray equations. In the limit of infinite frequencies, the rays have the usual semi-classical interpretation of being the paths of photons,null geodesics. At high but finite frequencies, corrections to these rays are expected. For light propagating in a medium,these corrections have been observed. In quantum mechanics,corrections in the context of adiabatic perturbations theory are well-studied.Wigner functions belong to the tools commonly used to capture them.In this talk, I will present a covariant version of Wigner-Weyl calculus which can,at least formally, be used in relativity.Corrections to geometrical optics can then be calculated,and one recovers results previously obtained by Oancea,et al., and Andersson, et al.. The effective ray equations can be recast as ...
Date: Thu, 29.04.2021
Time: 15:00
Duration: 60 min
Location:ZOOM-meeting: https://univienna.zoom.us/j/6540036841?pwd=SytyVkZJZzNyRG9lMm13ejlHeHRRUT09
Contact:Piotr Chrusciel, David Fajman

The imaginary part of the heavy-quark potential from real-time Yang-Mills dynamics
Speaker:Kirill Boguslavski (TU Wien)
Abstract:The suppression of heavy quark-antiquark bound states like bottomonium in heavy-ion collisions is an important observable for the quark-gluon plasma state. Theoretically, this can be quantified by the heavy-quark potential. In this talk, I will present our results on extracting its imaginary part using classical-statistical simulations of real-time Yang-Mills dynamics in classical thermal equilibrium. We compare our results to perturbation theory calculations in hard thermal loop formalisms. We find that, when considered as a function of m_D r, where m_D is the soft scale, the imaginary part of the heavy-quark potential becomes independent of the lattice spacing at sufficiently small r and agrees well with perturbative results. We finally relate the short-distance behavior of the potential to the heavy-quark transport coefficient κ, providing an estimate of the latter.
Date: Thu, 29.04.2021
Time: 16:30
Duration: 60 min
Location:https://tuwien.zoom.us/j/95482849369?pwd=SkU2WU5hMVJBQWsyVlFXRlRvQlIvdz09
Contact:Laura Donnay, Anton Rebhan

COSINUS - Novel cryogenic NaI detectors to throw light on the long-standing dark matter claim by DAMA/LIBRA
Speaker:Florian Reindl (ÖAW)
Abstract:Precision cosmology and astrophysics provide compelling evidence for the presence of dark matter in the universe. All proof of dark matter is based on its gravitational pull, but its nature remains a mystery to this date. Numerous direct dark matter searches aim to detect dark matter particles interacting in earth-bound detectors. DAMA/LIBRA is the only experiment which reports a potential positive dark matter signal. DAMA/LIBRA observes an annual modulation of their event rate, with an overwhelming statistical significance of 12.9 sigma, which fits the expectation of dark matter particles being present in the milky way. The DAMA/LIBRA signal is in tension with results from other experiments. However, a fully model-independent cross-check is absent so far and requires using the same target material: sodium iodide (NaI). The COSINUS experiment aims to do precisely that with novel cryogeni
Date: Fri, 30.04.2021
Time: 10:00
Duration: 45 min
Location:on-line
Contact:Jochen Schieck