
Calendar of Physics Talks Vienna
The Milky Way satellite galaxies  a serious challenge for the Cold Dark Matter cosmology 
Speaker:  Gerhard Hensler (Vienna) 
Abstract:  The socalled cosmological concordance model of a Cold Dark Matter
(CDM) dominated universe predicts a huge number of lowmass CDM
subhalos to exist and to surround massive galaxies with an almost
isotropic distribution. For our Milky Way and the neighboring Andromeda
galaxy these both requirements are significantly contrasted by
observations. Not only that the observed number of satellite galaxies
is orders of magnitude smaller  the socalled missingsatellite
problem – moreover, their spatial distributions are confined to thin
planes with coherent orbits. Nevertheless, unusually high masstolight
ratios are derived for the dwarf spheroidal galaxies around the Milky
Way, lending strong support of their large CDM content. In order to
approach consistency of the observational restrictions with the CDM
cosmology, over the recent years various scenarios are constructed ....

Date:  Thu, 08.01.2015 
Time:  14:00 
Duration:  60 min 
Location:  Arbeitsgruppe Gravitation, Währinger Strasse 17, Seminarraum A, 2. Stock, 1090 Wien 
Contact:  P.T. Chrusciel 
Improving CKM Unitarity Limits via LowEnergy Nuclear Physics 
Speaker:  Paul E. J. Finlay (KU Leuven) 
Abstract:  If the current threegeneration standard model is complete, then the CabibboKobayashiMaskawa matrix, which relates the mass and weakinteraction eigenstate of the quarks, should be unitary. The strictest test of unitarity currently comes from the toprow sum, with the most precise value for the largest element, Vud, coming from superallowed Fermi beta decays. The primary challenge towards future progress in CKM unitarity tests lies with understanding the theoretical isospinsymmetrybreaking (ISB) corrections, which currently dominate the uncertainty in the superallowed Ft values. Experimental input for the improvement of these calculations is possible, and this seminar will highlight some current and proposed lowenergy nuclear physics experiments aiming to contribute to the understanding and refinement of the ISB corrections. 
Date:  Thu, 08.01.2015 
Time:  15:30 
Location:  Atominstitut, Stadionallee 2, Wien 2, Hörsaal 
Contact:  H. Abele 
An introduction to Vlasov fields 
Speaker:  Jeremie Joudioux (University of Vienna) 
Abstract:  The EinsteinVlasov system is a good model to study the large scale behavior of our universe. After presenting the model in detail, I will describe the underlying geometry of the EinsteinVlasov system, with a focus on how the symmetries of the spacetime lift up to symmetries of Vlasov fields. In the final section, the Cauchy problem for the EinsteinVlasov system will be shortly presented, and the methods which are used to tackle the global existence and the stability of solutions will be shortly introduced. 
Date:  Thu, 08.01.2015 
Time:  16:00 
Duration:  60 min 
Location:  SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 810, A1040 Vienna) 
Contact:  Daniel Grumiller and Johanna Knapp 
Covariant loop quantum gravity 
Speaker:  Wolfgang Wieland (Pennsylvania State University) 
Abstract:  The talk gives an introduction to covariant loop quantum gravity, and presents recent developments in the field. The kinematical Hilbert space is derived from Ashtekar’s reformulation of general relativity in terms of SU(2) Yang—Mills variables. Quantum states of geometry live on the boundary of spacetime. Areas, angles and volumes turn into operators with discrete spectra. The dynamics is given in terms of spinfoam amplitudes, which represent the continuation of spinnetwork boundary states into the bulk. The most crucial open problem concerns the semiclassical limit: How can we recover general relativity plus quantum corrections? Studying this question, I found a proposal for a new action for discretized gravity in terms of spinors [arXiv:1407.0025]. The action is a onedimensional line integral over the edges of the discretization, and these edges turn into the worldlines of a system 
Date:  Fri, 09.01.2015 
Time:  15:15 
Duration:  60 min 
Location:  ESI 
Contact:  Nils Carqueville 
