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Calendar of Physics Talks Vienna
| Quantized cosmological space-times from Yang-Mills matrix models |
| Speaker: | Harold Steinacker (Univ. Wien) |
| Abstract: | We present simple solutions of IKKT-type matrix models describing quantized homogeneous and isotropic cosmologies with finite density of microstates and
a resolved Big Bang (BB). The BB arises from a signature change of the effective
metric on a fuzzy brane embedded in Lorentzian target space, in the presence of
a quantized 4-volume form. The Hubble parameter is singular at the BB, and
becomes small at late times. There is no singularity from the target space point
of view. One solution describes a linear coasting cosmology at late times, which
is remarkably close to observation. That solution consists of two sheets with
opposite intrinsic chiralities, which are connected in a Euclidean pre-big bang era.
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| Date: | Tue, 07.11.2017 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | TU Wien, Freihaus, SEM 136, 10. Stock, Wiedner Hauptstr. 8-10,1040 Wien |
| Contact: | S. Fredenhagen, D. Grumiller |
| Small-x Resummation from Effective Field Theory |
| Speaker: | Aditya Pathak (Univ. Wien) |
| Abstract: | im Rahmen des Teilchenphysikseminars |
| Date: | Tue, 07.11.2017 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, H. Neufeld |
| Bell's theorem for temporal order |
| Speaker: | Caslav Brukner (Vienna) |
| Abstract: | In general relativity causal relations between any pair of events is uniquely determined by locally predefined variables – the distribution of matter-energy degrees of freedom
in the events’ past light-cone. Under the assumption of locally predefined causal order,
agents performing freely chosen local operations on an initially local quantum state cannot violate Bell inequalities. However, superposition of massive objects can effectively lead to “entanglement” in the temporal order between groups of local operations, enabling the violation of the inequalities. This shows that temporal
orders between events can be “indefinite” in non-classical space-times.
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| Date: | Thu, 09.11.2017 |
| Time: | 13:30 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel |
| Background radiations in underground experiments |
| Speaker: | Dr. Vitaly Kudryavtsev (University of Sheffield) |
| Abstract: | Background radiations are known to pose a threat to high-sensitivity experiments for rare event searches, such as dark matter, neutrinoless double-beta decay and neutrino detectors. These radiations are caused by minute concentrations of radioactive isotopes in the detector components (including the detector sensitive volume itself) and surrounding materials. They can also be caused by cosmic-rays either underground by producing background events indistinguishable from the expected signal, or at the surface by activating materials that are used in the detector construction. In this talk, I will review mechanisms and computer codes for gamma-ray and neutron production and transport. I will also discuss the background due to cosmic rays including activation of materials at the surface. As an example of background rate calculations, I will briefly summarise the work of the LZ Collaboration. |
| Date: | Thu, 09.11.2017 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Seminar Room, Institute of High Energy Physics (HEPHY), Wohllebengasse 12-14, 1040 Wien |
| Contact: | Holger Kluck |
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