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Calendar of Physics Talks Vienna
| K3 string theories, symmetries and wall crossing |
| Speaker: | Roberto Volpato (Padua University) |
| Abstract: | I will consider a large class of four dimensional N=4 string models obtained from compactifications of type II string theory on $K3\times T^2$ and orbifolds thereof. I will show that the multiplicities of 1/4 BPS states in such models can be determined (almost) uniquely by imposing some simple consistency condition. The main ingredient in this derivation is a careful analysis of the wall crossing phenomenon. These results lead to a better understanding of the action of discrete groups of symmetries on the BPS spectrum of K3 string models and might shed some light on the mysterious Umbral moonshine conjectures. This talk is based on joint work with Natalie Paquette and Max Zimet. |
| Date: | Mon, 08.05.2017 |
| Time: | 15:00 |
| Duration: | 60 min |
| Location: | SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna) |
| Contact: | Timm Wrase |
| Moduli spaces of stable bundles for intermediate values of c_2 |
| Speaker: | Carlos Simpson (Université de Nice) |
| Abstract: | The moduli spaces of stable vector bundles on surfaces have a well-understood structure—generically
smooth of the expected dimension, and irreducible—for large values of c2; and they are empty for c2 less than
the Bogomolov-Gieseker bound.We’ll discuss joint work with Nicole Mestrano about understanding the structure
for all values of c2 in between, for generic hypersurfaces of low degree in P3. |
| Date: | Tue, 09.05.2017 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Erwin Schrödinger Int. Institute for Mathematics and Physics, Boltzmanngasse 9, 1090 Wien, Boltzmann lecture hall |
| Contact: | ESI, U Vienna |
| Twistors and Conformal Higher-Spin Theory |
| Speaker: | Tristan McLoughlin (Trinity College Dublin) |
| Abstract: | Higher-spin fields can play an important role in effective field theories and increasingly
are of interest due to their appearance in recent studies of holography. Understanding their
interactions is however often involved and searching for alternative formulations could be
very useful. In this talk we will consider one such formulation, namely twistors. After giving
a general introduction to the use of twistors in describing the dynamics of massless field theories, we will focus on the construction of off-shell actions directly in twistor space including a recent higher-spin generalisation of self-dual Weyl gravity. We will show how this formulation produces the expected flat space-time spectrum and linearised symmetries.
In analogy with the known embedding of Einstein gravity inside Weyl gravity, we identify
a ghost free sub-sector of the conformal higher-spin theory and . . . |
| Date: | Tue, 09.05.2017 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | S. Fredenhagen, H. Steinacker |
| Factorization and resummation for massive quark effects in exclusive Drell-Yan |
| Speaker: | Daniel Samitz (Univ. Wien) |
| Abstract: | im Rahmen des Teilchenphysikseminars |
| Date: | Tue, 09.05.2017 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, H. Neufeld |
| Strong Cosmic Censorship and the initial singularity in Bianchi spacetimes |
| Speaker: | Katharina Radermacher (Stockholm) |
| Abstract: | For given initial data to Einstein's field equations, one can find a spacetime solving these equations, and one can do so in a unique way (up to isometries) if one assumes the spacetime to be maximal globally hyperbolic. Both statements were proven by Choquet-Bruhat and Geroch in the 1950s and 60s. When dropping the additional condition of global hyperbolicity, it is an open question whether one can extend this spacetime, possibly in a non-unique way. Strong Cosmic Censorship conjectures that no such extension exists, at least not for generic initial data. In my talk, I focus on spacetimes where the initial data is symmetric under the action of a three-dimensional Lie group (a so-called Bianchi spacetime) and the stress-energy tensor is that of vacuum or a perfect fluid. I present results proving the Strong Cosmic Censorship conjecture for orthogonal Bianchi class B spacetimes and . . . |
| Date: | Thu, 11.05.2017 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel |
| Positivity and singularities in Hodge theory |
| Speaker: | Phillip Griffiths (Institute for Advanced Studies, Princeton and University of Miami) |
| Abstract: | The bundles that arise in Hodge theory tend to have signs (say positive). The singularities that arise have the properties: they should be thought of like wave-front-sets in cotangent bundles; they are mild; and they increase the positivity. These properties with some applications to algebraic geometry will be discussed. |
| Date: | Fri, 12.05.2017 |
| Time: | 11:00 |
| Duration: | 60 min |
| Location: | Erwin Schrödinger Int. Institute for Mathematics and Physics, Boltzmanngasse 9, 1090 Wien, Boltzmann lecture hall |
| Contact: | ESI, U Vienna |
| Black hole entropy from matter entropy |
| Speaker: | Jose P. S. Lemos (Physics Department, Instituto Superior Tecnico, Univ. of Lisbon) |
| Abstract: | im Rahmen des Lunchseminars der Gravitationsphysik: Black hole entropy S is one of the most fascinating issues in contemporary physics, as one
does not yet strictly know what are the degrees of freedom at the fundamental microlevel,
nor where are they located precisely. In addition, extremal black holes, in contrast to non-
extremal ones, present a conundrum, as there are two mutually inconsistent results for the
entropy of extremal black holes. There is the usual Bekenstein-Hawking S = A/4 value,
where A is the horizon area, obtained from string theory and other methods, and there is the
prescription S = 0 obtained from Euclidean arguments. In order to better understand black
hole entropy in its generality, we exploit a matter based framework and use a thermodynamic
approach for an electrically charged thin shell. We find the entropy function for such a system. We then take . . . |
| Date: | Fri, 12.05.2017 |
| Time: | 13:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel |
| Low-energy hints of physics beyond the Standard Model |
| Speaker: | Gino Isidori (Univ. Zürich) |
| Abstract: | im Rahmen des Teilchenphysikseminars: In the last few years a series of hints of deviations from the Standard
Model in B-meson decays have been reported by experiments.
I review these hints, focusing in particular on the tests of Lepton
Flavor Universality, addressing both Standard Model uncertainties
and discussing possible New Physics interpretations.
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| Date: | Fri, 12.05.2017 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, H. Neufeld |
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