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Calendar of Physics Talks Vienna
| Path integrals for Wilson lines and Wilson surfaces |
| Speaker: | Anton Alekseev (University of Geneva) |
| Abstract: | im Rahmen des Seminars für Mathematische Physik: Wilson lines in gauge theory admit several path integral presentations based on
the theory of coadjoint orbits. We will discuss an interpretation of these theories
as 2-dimensional sigma-models using equivariant cohomology and consider toy
model applications in 2-dimensional Yang-Mills theory.
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| Date: | Tue, 16.05.2017 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | S. Fredenhagen, H. Steinacker |
| Magneto-optical infrared studies of the Weyl semimetals TaAs, TaP and NbP |
| Speaker: | A. V. Pronin (1. Physikalisches Institut, Universität Stuttgart, Germany) |
| Abstract: | We report on infrared and magnetotransport measurements of the Weyl semimetals TaAs, TaP, and NbP in zero magnetic field and in fields of up to 30 T. In all compounds, we can reliably trace the optical transitions between different Landau levels. The transition frequencies demonstrate a square-root field dependence, typical for the linearly dispersed bands. In TaP, we can also see a sizeable shift of the plasma edge in magnetic field and interplay between this plasma-edge shift and
the Landau-level transitions. We compare the optical spectra of the three compounds, describe the spectra by the recent models for the (magneto)optical response of Weyl semimetals, and extract such parameters as the Fermi velocities of the carriers in the Weyl bands and the positions of the Fermi levels relative to the Weyl points. |
| Date: | Wed, 17.05.2017 |
| Time: | 16:00 |
| Duration: | 45 min |
| Location: | Seminarraum DC rot 07 (Freihaus, roter Bereich, 7. OG), Wiedner Hauptstraße 8-10, 1040 Wien |
| Contact: | Andrei Pimenov |
| The hunt for the elusive photon-photon elastic scattering: the PVLAS experiment and more |
| Speaker: | Prof. Edoardo Milotti (Dipartimento di Fisica, Università di Trieste and INFN-Sezione di Trieste) |
| Abstract: | Photon-photon scattering is forbidden in classical electromagnetism, but it becomes possible in quantum field theory thanks to the fluctuations of charged matter fields. The first theoretical calculations are associated with the names of Euler, Heisenberg, and Weisskopf, and date back to more than 80 years ago, but to date a laboratory measurement is still missing. The predicted effect is extremely minute with visible photons, and measurements require an exceedingly high level of precision. Currently, a bunch of experimentalists are painstakingly trying to get to the required level of precision. There is much at stake: by reaching this difficult experimental goal we could open a new window on the nature of quantum vacuum, and maybe discover some essential clues on dark matter.
In this talk...[complete last paragraph available at https://indico.smi.oeaw.ac.at/event/217/] |
| Date: | Wed, 17.05.2017 |
| Time: | 17:00 |
| Duration: | 60 min |
| Location: | Stefan-Meyer-Institut, Boltzmanngasse 3, 1090 Wien, Seminarraum 3-2-08 (2. Stock) |
| Contact: | Prof. Dr. Eberhard Widmann, Dr. Martin Simon |
| Unifying inflation with the axion, dark matter, baryogenesis and the seesaw mechanism |
| Speaker: | Carlos Tamarit (IPPP Durham) |
| Abstract: | A minimal extension of the standard model (SM) with a single new mass scale and providing a complete and consistent picture of particle physics and cosmology up to the Planck scale is presented. We add to the SM three right-handed SM-singlet neutrinos, a new vectorlike color triplet fermion, and a complex SM-singlet scalar σ that stabilizes the Higgs potential and whose vacuum expectation value at ∼1011 GeV breaks lepton number and a Peccei-Quinn symmetry simultaneously. Primordial inflation is produced by a combination of σ (nonminimally coupled to the scalar curvature) and the SM Higgs boson. Baryogenesis proceeds via thermal leptogenesis. At low energies, the model reduces to the SM, augmented by seesaw-generated neutrino masses, plus the axion, which solves the strong CP problem and accounts for the dark matter in the Universe. |
| Date: | Thu, 18.05.2017 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | HEPHY, Nikolsdorfer Gasse 18, 1050 Wien - Bibliothek |
| Contact: | Josef Pradler |
| Gravitational Memory, Information, and Black Holes |
| Speaker: | Stefan Hollands (Leipzig) |
| Abstract: | A burst of gravitational radiation passing through an arrangement of freely falling test
masses far from the source will cause a permanent displacement of the masses, called
the ``gravitational memory''. It has recently been found that this memory is closely related
to the change in the so called ``super-translation'' charge carried by the spacetime, where ``super-translations'' here refer to an unexpected enlargement of the asymptotic symmetries
of general relativity beyond the expected asymptotic Poincare-transformations, known
already since the work of Bondi et al. in the early 60s (no relation with ``supersymmetry'').
I will describe these concepts from an intuitive perspective and point out that super-translations, as well as gravitational memory, are a phenomenon that is unique to relativity
in 3+1, but not higher, dimensions. I close the talk by outlining the relation ... |
| Date: | Thu, 18.05.2017 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel |
| Strongly coupled Weyl semi-metals |
| Speaker: | Francisco Pena-Benitez (INFN Perugia) |
| Abstract: | In this talk I will review the main properties of Weyl semimentals. Including a recent experiment which claims the observation of the so-called mixed gauge-gravitational anomaly in a Weyl semimetal. Then I’ll discuss a holographic model that realize some of the features of the these materials. In particular, I will analyze the electrical conductivity, its frequency dependence and phase diagram; I will finish discussing some predictions of the model.
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| Date: | Thu, 18.05.2017 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | 10th floor seminar room in yellow tower of TU Wien Freihaus (Wiedner Hauptstrasse 8-10, A-1040 Vienna) |
| Contact: | ayan.mukhopadhyay@tuwien.ac.at |
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