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Calendar of Physics Talks Vienna
| Horror vacui: instabilities in scale-separated Casimir compactifications |
| Speaker: | Ivano Basile (MPI Munich) |
| Abstract: | Finding reliable scale-separated vacua with no moduli in the string landscape is a considerable challenge, yet it is essential to connect string theory to our universe. Among several attempts, toroidal compactifications supported by fluxes and Casimir energy stand out for their simplicity and degree of parametric control. In particular, there exist simple such compactifications of eleven-dimensional supergravity leading to non-supersymmetric weakly curved anti-de Sitter solutions in four dimensions. I will show that these solutions are perturbatively (and non-perturbatively) unstable, and thus do not pertain to bona fide four-dimensional effective field theories. |
| Date: | Tue, 03.03.2026 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-HS, Boltzmanngasse 5, 1090 Wien, 5.Stock |
| Contact: | S. Fredenhagen, M. Sperling |
| The semiclassical limit of the Dirac equation“ |
| Speaker: | Jakob Möller (CMLS, École Polytechnique, Palaiseau) |
| Abstract: | The Dirac equation was discovered by Paul Dirac in 1928 in order to find a first-order in time Lorentz-invariant Schrödinger equation for particles with half-integer spin. He discovered that the scalar wave function of the Schrödinger equation had to be replaced by a 4-component vector-valued wave function, which includes the two spin states of a charged fermion and predicted its antiparticle. The vector-valued nature implies that the Dirac operator is matrix-valued. In order to treat the semiclassical limit we transform the Dirac equation into the Wigner equation for the matrix-valued Wigner transform, which converges to the positive definite Wigner matrix measure. The latter obeys a matrix-valued Liouville equation where the oscillating part of the Wigner equation converges to a Lagrange multiplier that maintains the constraint that the Wigner matrix commutes with the Weyl symbol of th |
| Date: | Wed, 04.03.2026 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Seminar Room A, Waehringer Str. 17, 1090 Wien, 2nd floor |
| Contact: | D. Fajman |
| From Matrix Models to Gaussian Molecules and the Einstein-Hilbert Action |
| Speaker: | Manfred Herbst |
| Abstract: | A matrix model on a D-dimensional Riemannian manifold is introduced, whose free energy is related to the physics of Gaussian molecules and shown to result in the Einstein-Hilbert action with cosmological constant. The gravitational and the cosmological constants are both formally determined to all orders in the string perturbation expansion and expressed in terms of graph combinatorics. |
| Date: | Thu, 05.03.2026 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | TU Wien, Wiedner Hauptstrasse 8-10, seminar room 10th floor (yellow tower) |
| Contact: | Anton Rebhan, Ankit Aggarwal |
| Fractional Multiscale Many-Body Quantum Materials: From Phase Transitions to Causality |
| Speaker: | Lincoln Carr (Colorado School of Mines) |
| Abstract: | Fractional multiscale materials are common in classical and biological systems, being in fact quite typical in disparate natural systems ranging from anomalous diffusion of pollutants in ground water systems to faster than expected infection rates of catheters in hospital settings. Until now multiscale quantum problems of this nature have appeared to be out of reach at the many-body level relevant to strongly correlated materials and current quantum information devices.
In fact, they can be modeled with q-th order fractional derivatives, as I demonstrate in the first part of this talk, treating classical and quantum phase transitions in a fractional Ising model for 0 |
| Date: | Fri, 06.03.2026 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Nadine Hilmar |
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