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Calendar of Physics Talks Vienna
| Boundary RG flows, Kondo and AdS/CFT |
| Speaker: | Christian Northe (Univ. Würzburg) |
| Abstract: | Not only has the Kondo model played a major role in condensed matter physics, but it has also sharpened our techniques for dealing with boundaries and interfaces in CFT and string theory. Within CFT, the Kondo effect is described via branes which acquire additional dimensions. Starting from the NS5/F1 system, we have found the BPS solutions to the DBI system describing RG flows between D1- and D3-brane solutions and worked out their g-factors. Using a class of half BPS solutions provided we find corresponding backreacted supergravity interface solutions for both types of branes and work out their central charges and g-factors. Our approach provides an explicit example of a Kondo-like CFT defect, with an explicit gravitational dual. |
| Date: | Tue, 27.11.2018 |
| Time: | 13:45 |
| Duration: | 60 min |
| Location: | TU Wien, Getreidemarkt 9, Maschinenbaugebäude, 1. Stock, HS Kleiner Schiffbau |
| Contact: | S. Fredenhagen, D. Grumiller |
| Kirkwood -Buff integrals from Molecular Simulations |
| Speaker: | Sondre K. Schnell |
| Abstract: | Kirkwood -Buff (KB) theory was originally derived by Kirkwood and Buff [1] and can be used to relate nanoscale structure properties (i.e. radial distribution functions) of multicomponent isotropic liquids to macroscopic thermodynamic quantities like derivatives of chemical potential with respect to composition, partial molar volumes, and isothermal compressibility. Kirkwood-Buff theory was originally derived for open systems in the thermodynamic limit, but even with those limitations it has become a popular method to relate thermodynamic and structure properties using molecular simulations and experiments.
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| Date: | Tue, 27.11.2018 |
| Time: | 13:45 |
| Duration: | 60 min |
| Location: | Lecture room, Sensengasse 8, ground floor, 1090 Wien |
| Contact: | Claudia Rennhofer, (Walter Penits) |
| Massive Quark Jet Function at Two Loops |
| Speaker: | Christopher Lepenik (Univ. Wien) |
| Abstract: | The jet function is a crucial ingredient of inclusive cross section factorization formulas for QCD processes involving a large scale hierachy between the jet invariant mass and the total center of mass energy. It describes the collinear particles in a jet and is universal in the sense that it is independent of the details of the hard process and that the same jet function is valid for any observable that effectively reduces to a measurement of the jet invariant mass in the collinear limit.In the limit of massless quarks all factorization formula ingredients are known at least up to two-loop order for many processes of interest, enabling N^3LL order resummation of large logarithms. For massive quarks however, the jet function is known only up to one-loop, making the two-loop correction the missing piece for N^3LL resummation with full mass dependence. In this talk I will present the .... |
| Date: | Tue, 27.11.2018 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, S. Plätzer |
| STATIC VACUUM SPACETIMES WITH POSITIVE COSMOLOGICAL CONSTANT |
| Speaker: | Stefano Borghini (Università degli Studi di Trento, Italy) |
| Abstract: | Static vacuum metrics are solutions to the Einstein Field Equations with vanishing
stress-energy tensor and featuring a very special metric structure (warped product).
Such a structure induces a natural foliation of the spacetime into space-like slices
which are all isometric to each other, so that the corresponding physical universe
is static. We discuss the problem of the classi_cation of such solutions in the case of
positive cosmological constant. To this end, we introduce an appropriate notion of
mass, showing that it satis_es a Positive Mass Statement and a Riemannian Penrose
{like inequality. Building on this, we prove a uniqueness result for the Schwarzschild
{de Sitter solution, which is somehow reminiscent of the well known Black Hole
Uniqueness Theorem for the Schwarzschild solution.
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| Date: | Thu, 29.11.2018 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel, D. Fajman |
| Tension Between a Vanishing Cosmological Constant and Non-Supersymmetric Heterotic Orbifolds |
| Speaker: | Stefan Groot-Nibbelink (Rotterdam) |
| Abstract: | We investigate under which conditions the one-loop cosmological constant vanishes for heterotic strings on non-supersymmetric toroidal orbifolds. To obtain model-independent results, we require that each orbifold sector preserves at least a single Killing spinor, but not always the same one. The existence of such Killing spinors is related to the representation theory of the point groups that underly the orbifold geometries. Going through all inequivalent (Abelian and non-Abelian) point groups of six-dimensional toroidal orbifolds shows that this is never possible: For any non-supersymmetric orbifold there is always (at least) one sector, that does not admit any Killing spinor and hence gives a non-vanishing contribution to the partition function which most likely results in a too large cosmological constant. |
| Date: | Fri, 30.11.2018 |
| Time: | 13:30 |
| Duration: | 60 min |
| Location: | Small seminar room, 5th floor, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna |
| Contact: | Stefan Fredenhagen and Johanna Knapp |
| PUBLIC LECTURE: Black Holes, Fundamental Physics and the Information Paradox |
| Speaker: | Malcolm Perry (Cambridge University) |
| Date: | Fri, 30.11.2018 |
| Time: | 18:00 |
| Location: | Festsaal der Österreichischen Akademie der Wissenschaften, Dr. Ignaz Seipel-Platz 2, 1010 |
| Contact: | Anton Rebhan |
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