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Calendar of Physics Talks Vienna
| A String Theory That Isn't About String |
| Speaker: | Soo-Jong Rey (IBS, Daejeon & KAIST & Seoul National U.) |
| Abstract: | Folklore is that string is an extended object, so it involves infinitely many particle excitations. In this talk, I show that this is not necessarily the case. I consider a novel string theory whose quantization is based upon chirally asymmetric worldsheet vacuum. This results in a theory that involves just a pair of massive gravitons in addition to the massless graviton, two-form field and dilaton. I will show that this novel string theory defines the double field theory at finite string tension, and ambitwistor string theory at infinite string tension. I also compute one-loop partition function, and show that the modular invariance is no longer maintained. |
| Date: | Mon, 12.06.2017 |
| Time: | 11:30 |
| Duration: | 75 min |
| Location: | ESI, Boltzmann lecture hall |
| Contact: | Daniel Grumiller |
| Black hole microstates and a rough end to spacetime |
| Speaker: | Andrea Puhm (Harvard U.) |
| Abstract: | The study of supersymmetric black holes in string theory has been a useful arena for the search for the correct microscopic description of black holes, with one of its greatest triumphs being the explicit stringy counting by Strominger and Vafa of the number of microstates of the D1-D5-P system which famously agrees precisely with the Bekenstein-Hawking entropy of the naive black hole solution. The fuzzball program is an attempt to describe these microstates at finite coupling with the extended objects of string theory modifying the structure of the black hole horizon by replacing it with an end to spacetime. An important open question is what fraction of these microstates is smooth, contains singularities corresponding to D-brane sources or is arbitrarily quantum and/or strongly curved. In this talk I will use entropic and dynamic arguments to address this question. |
| Date: | Mon, 12.06.2017 |
| Time: | 14:30 |
| Duration: | 60 min |
| Location: | ESI, Boltzmann lecture hall |
| Contact: | Daniel Grumiller |
| Speaker: | Ricardo Troncoso (CECs Valdivia) |
| Date: | Mon, 12.06.2017 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | ESI, Boltzmann lecture hall |
| Contact: | Daniel Grumiller |
| Quantum-Gas Microscopes - Quantum-Simulation with Single-Particle Access |
| Speaker: | Stefan Kuhr (CoQuS) |
| Abstract: | The great challenge to obtain full single-site resolution and single-atom control in optical lattices was overcome by the development of quantum-gas microscopes and I will present an overview of the recent developments in this field. I will also present how we achieved single-atom-resolved fluorescence imaging of fermionic potassium-40 atoms using electromagnetically-induced-transparency (EIT) cooling,and a new way of Raman gray-molasses cooling on the D2-line, and report on our progress towards the study of strongly correlated fermionic quantum systems and their out-of-equilibrium dynamics. |
| Date: | Mon, 12.06.2017 |
| Time: | 16:30 |
| Duration: | 120 min |
| Location: | Atominstitut, Stadionallee 2, 1020 Vienna |
| Contact: | CoQuS-Team |
| Towards a general AdS/Ricci-flat correspondence |
| Speaker: | Kostas Skenderis (Southampton U.) |
| Abstract: | The AdS/Ricci-flat (AdS/RF) correspondence is a map between families of asymptotically locally AdS solutions on a torus and families of asymptotically flat spacetimes on a sphere. In this talk I will discuss how to relax these restrictions for linearized perturbations around solutions connected via the original AdS/RF correspondence. This correspondence should allow us to develop a detailed holographic dictionary for asymptotically flat spacetimes. |
| Date: | Tue, 13.06.2017 |
| Time: | 10:00 |
| Duration: | 60 min |
| Location: | ESI, Boltzmann lecture hall |
| Contact: | Daniel Grumiller |
| Exact entropy of 1/4-BPS black holes in N=4 supergravity and the mixed Rademacher expansion |
| Speaker: | Valentin Reys (U. Milano) |
| Abstract: | I will present some recent developments in computing the exact entropy of dyonic 1/4-BPS black holes in four-dimensional N=4 supergravity theories originating from Type IIB string theory compactified on K3 x T2. The exact entropy is obtained in the Quantum Entropy Function formalism by means of supersymmetric localization techniques. The result can then be compared to the degeneracy of the brane/momentum system making up the black hole in the string theory picture. Such degeneracies are given by the Fourier coefficients of so-called mock Jacobi forms, a concept I will review. An exact formula for the coefficients can be obtained via a suitable generalization of the Hardy-Ramanujan-Rademacher circle method which takes into account the mock character of the counting functions. After presenting these results, I will outline some discrepancies (at sub-leading order in the charges)... |
| Date: | Tue, 13.06.2017 |
| Time: | 11:30 |
| Duration: | 60 min |
| Location: | ESI, Boltzmann lecture hall |
| Contact: | Daniel Grumiller and Abhiram M Kidambi |
| Non-conformal shock wave collisions |
| Speaker: | Maximilian Attems (Barcelona U. & ICC ) |
| Abstract: | Understanding the out of equilibrium formation of a strongly coupled Quark-Gluon-Plasma is an important theoretical challenge, in particular in light of the upcoming massive experimental effort by both the LHC and RHIC on studying the extreme states of matter formed by ultra-relativistic heavy-ion collisions. In this talk I will use the gauge/gravity duality to model the first stage of a heavy ion collision by a collision of gravitational shockwaves in numerical relativity. This investigation of collisions of sheets of energy density in a non-conformal theory with a gravity dual is the first non-conformal holographic simulation of a heavy ion collision. I will discuss the new physics that arises (as compared to the much simpler conformal case) such as a new plasma relaxation channel, the equilibration of the conformal symmetry breaking scalar condensate and the presence of a sizeable bul |
| Date: | Tue, 13.06.2017 |
| Time: | 14:30 |
| Duration: | 60 min |
| Location: | SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna) |
| Contact: | Daniel Grumiller |
| Nonviolent unitarization: postulates to soft quantum structure of black holes |
| Speaker: | Steve Giddings (UC Santa Barbara) |
| Abstract: | The problem of preserving unitary evolution in the presence of an evaporating black hole remains a key problem in quantum gravity, expected to point to new fundamental principles. It has been argued that unitary evolution implies breakdown of spacetime at the horizon (a "firewall"), or other large near-horizon effects. I explore a basic set of postulates, including a "correspondence principle" for observers falling into large black holes, and find the possibility that unitarization occurs via weak interactions between quantum states of a black hole and degrees of freedom in its environment. |
| Date: | Tue, 13.06.2017 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | ESI, Boltzmann lecture hall |
| Contact: | Daniel Grumiller |
| Dispersion relations for hadronic light-by-light scattering and the muon g-2 |
| Speaker: | Massimiliano Procura (CERN) |
| Abstract: | im Rahmen des Teilchenphysikseminars |
| Date: | Tue, 13.06.2017 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, H. Neufeld |
| Can quantum-gravitational effects be observed in the cosmic microwave background? |
| Speaker: | Claus Kiefer (Cologne U.) |
| Abstract: | In any approach to quantum gravity, it is crucial to search for observational effects. In my talk, I discuss how quantum-gravitational contributions to the anisotropy spectrum of the cosmic microwave background arise in the framework of quantum geometrodynamics (Wheeler-DeWitt equation). A scenario of slow-roll inflation is assumed. I derive concrete predictions for the power spectrum and other cosmic quantities and discuss their observability. I also present a brief comparison with other approaches. |
| Date: | Wed, 14.06.2017 |
| Time: | 10:00 |
| Duration: | 60 min |
| Location: | ESI, Boltzmann lecture hall |
| Contact: | Daniel Grumiller |
| Some unexpected aspects of mass and proper time in quantum mechanics, and why they should be considered as dynamical objects, represented by Hermitian operators |
| Speaker: | Daniel Greenberger (City Coll. N.Y.) |
| Abstract: | In classical physics, and non-relativistic quantum mechanics, mass enters the theory as a simple parameter. This leads to paradoxical behavior, which can only be cured by considering it as an operator. Proper time is determined by geometry, but it also has no dynamical role to play, which also leads to paradoxes. Again the cure is to consider it as an operator. The standard formalism is perfectly attuned to extend to accomodate them as such, where they will be conjugate variables, which leads to new phenomena. |
| Date: | Wed, 14.06.2017 |
| Time: | 14:30 |
| Duration: | 60 min |
| Location: | ESI, Boltzmann lecture hall |
| Contact: | Markus Aspelmeyer and Caslav Brukner and Daniel Grumiller |
| Boundary conditions for General Relativity on AdS3 and the KdV hierarchy |
| Speaker: | Alfredo Perez (CECs Valdivia) |
| Abstract: | It is shown that General Relativity with negative cosmological constant in 3D admits a new family of boundary conditions being labeled by a nonnegative integer k. Gravitational excitations are then described by boundary gravitons that fulfill the equations of the k-th element of the KdV hierarchy. In particular, k = 0 corresponds to the Brown-Henneaux boundary conditions so that excitations are described by chiral movers. In the case of k = 1, the boundary gravitons fulfill the KdV equation and the asymptotic symmetry algebra turns out to be infinite-dimensional, abelian and devoid of central extensions. The latter feature also holds for the remaining cases that describe the hierarchy (k > 1). Our boundary conditions then provide a gravitational dual of two noninteracting left and right KdV movers, and hence, boundary gravitons possess anisotropic Lifshitz scaling with dynamical exponent |
| Date: | Wed, 14.06.2017 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | ESI, Boltzmann lecture hall |
| Contact: | Daniel Grumiller |
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