|
Calendar of Physics Talks Vienna
| Loop Quantum Gravity and the Continuum |
| Speaker: | Wolfgang Wieland (Perimeter Institute for Theoretical Physics, Waterloo, Canada) |
| Abstract: | One of the main open problems in loop quantum gravity is to reconcile the fundamental quantum discreteness of space with general relativity in the continuum. In this talk, I present recent progress regarding this issue: I will explain, in particular, how the discrete spectra of geometric observables that we find in loop gravity can be understood from a conventional Fock quantisation of gravitational edge modes on a null surface boundary. On a technical level, these boundary modes are found by considering a quasi-local Hamiltonian analysis, where general relativity is treated as a Hamiltonian system in domains with inner null boundaries. The presence of such null boundaries requires then additional boundary terms in the action. Using Ashtekar’s original SL(2,C) self-dual variables, I will explain that the natural such boundary term is nothing but a kinetic term for a spinor . . . . |
| Date: | Tue, 13.11.2018 |
| Time: | 13:45 |
| Duration: | 60 min |
| Location: | TU Wien, Getreidemarkt 9, Maschinenbaugebäude, 1. Stock, HS Kleiner Schiffbau |
| Contact: | S. Fredenhagen, D. Grumiller |
| Double parton scattering: basics and recent theory developments |
| Speaker: | Markus Diehl (DESY, Hamburg) |
| Abstract: | im Rahmen des Teilchenphysikseminars: I give a brief introduction into the double parton scattering mechanism in proton-proton collisions, and then discuss several advances in their theoretical description. Aspects to be discussed are factorisation, evolution, and the distinction between single and double hard scattering. |
| Date: | Tue, 13.11.2018 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, S. Plätzer |
| The Friedrich-Butscher method for the construction of initial data in General Relativity |
| Speaker: | Jarrod Williams (ESI) |
| Abstract: | im Rahmen des Literaturseminars für Gravitationsphysik:
The construction of initial data for the Cauchy problem in General Relativity is an interesting problem from both the mathematical and physical points of view. As such, there have been numerous methods studied in the literature - the "Conformal Method" of Lichnerowicz-Choquet-Bruhat-York and the "gluing" method of Corvino-Schoen being
perhaps the best-explored.
In this talk I will describe an alternative, perturbative, approach proposed by A. Butscher and H. Friedrich, and show how it can be used to construct non-linear perturbations of initial data for spatially-closed analogues of the "k = -1" FLRW spacetime. Time permitting, I will discuss possible refinements/extensions of the method, along with its generalisation to the full Conformal Constraint Equations of
H. Friedrich.
|
| Date: | Thu, 15.11.2018 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel, D. Fajman |
|