|
Calendar of Physics Talks Vienna
| Logarithmic Doublets in Celestial CFT |
| Speaker: | Beniamino Valsesia (SISSA Trieste) |
| Abstract: | The AdS/CFT correspondence is a duality stating that quantum gravity in an AdS spacetime is equivalent to a conformal field theory (CFT) on its boundary. Its development has been a central topic in theoretical physics for the past 25 years. However, its extension to non-AdS backgrounds, such as flat space, remains challenging. A recent proposal suggests that 4D quantum gravity in flat space could be dual to a 2D celestial CFT on the sphere. The discovery of deep connections between Weinbergâs soft theorems and asymptotic charge conservation established a direct link between bulk soft operators and celestial CFT symmetry generators, including the stress tensor. This led to the computation of the CCFT central charge, which was found to be zero. Since a unitary CFT with vanishing central charge is trivial, alternative nontrivial CFTs must be considered. One such class is logarithmic CFTs (L |
| Date: | Tue, 11.03.2025 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-HS, Boltzmanngasse 5, 1090 Wien, 5.Stock |
| Contact: | S. Fredenhagen, M. Sperling |
| Semileptonic decays at the frontier |
| Speaker: | Jack Jenkins (University of Siegen) |
| Abstract: | In this talk I will outline some of the challenges facing higher-precision extractions of CKM matrix elements and effective neutral-current couplings from inclusive B decays and rare semileptonic kaon decays, which persist despite increasingly precise perturbative information for these quantities. In the B sector, phenomenological extractions of local power correction parameters are the largest bottleneck for testing the SM with the rare mode B->X ll, and I outline an approach to scrutinize their extraction from kinematical moments of charged-current B decays. I will also discuss a dispersive approach to the nonlocal contribution to rare kaon decays K->pi ll and K->pi nu nu, and similar strategies based on chiral dynamics applied to the B -> pi form factors at high recoil. |
| Date: | Tue, 11.03.2025 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-HS, Boltzmanngasse 5, 1090 Wien, 5.Stock |
| Contact: | A. Hoang, M. Procura |
| A panoramic view of low dimensional manifolds - CANCELLED!! |
| Speaker: | Willi Kepplinger (University of Vienna) |
| Abstract: | he character and status of very simple sounding questions in manifold theory depends crucially on the dimension of the manifold. An illustrative example is the famous Jordan curve theorem which roughly speaking states that a topological embedding of S^1 into R^2 separates R^2 into a bounded component (which is homeomorphic to a disk) and an unbounded one. Naively speaking this theorem seems obvious, if annoying to prove. In reality, it is a miracle it is true in the first place as corresponding statements in dimension 3 and higher are simply wrong. In this talk I will try to give an overview over questions in low dimensional topology (such as existence and uniques of smooth structures, classification of manifolds) and how these depend on the dimension. |
| Date: | Wed, 12.03.2025 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Seminar Room A, Waehringer Str. 17, 1090 Wien, 2nd floor |
| Contact: | P. Chrusciel, D. Fajman |
| Universal scaling laws for correlated decays of many body quantum systems |
| Speaker: | Cosimo Rusconi (Columbia University) |
| Abstract: | Increasing the density of quantum devices opens avenues to explore novel regimes of many-body quantum dynamics and enhance the performance of various quantum applications such as precise sensing. At the same time, this effort poses new challenges as densely packed systems exhibit correlated dissipation, significantly impacting the decay rate of correlated quantum states. It is thus natural to ask: What is the maximum decay rate of a system with correlated dissipation? Addressing this question for large numbers of particles is however complicated by the exponential scaling of the Hilbert space dimension. In this talk, I will present an alternative method that circumvents this difficulty. We reformulate the problem of maximal decay rate into finding the ground state energy of a 2-local Hamiltonian. Leveraging ideas from quantum approximation theory and semidefinite programming relaxations |
| Date: | Wed, 12.03.2025 |
| Time: | 16:00 |
| Duration: | 45 min |
| Location: | Freihaus Building, Seminar room yellow 10th floor |
| Contact: | Carlos Gonzalez Ballestero |
| Quantum-limited measurements for open quantum simulators with tunnel-coupled condensates |
| Speaker: | Maximilian Prüfer (TU Wien, Atominstitut) |
| Abstract: | Quantum measurements are usually realized by coupling an isolated quantum system to an
auxiliary meter system. Thus, weak, repeated measurements present an intriguing pathway
toward controlled open quantum simulators. We present a quantum-limited generalized
measurement scheme for tunnel-coupled superfluids. Our results reveal the capability to
detect quantum properties and dynamical evolution. Finally, we will discuss progress
toward achieving repeated or continuous measurements with local control, aiming to create
controllable open quantum simulators in the future.
|
| Date: | Wed, 12.03.2025 |
| Time: | 16:15 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Maximilian Prüfer |
| Symmetries in Quantum Gravity |
| Speaker: | Markus Josef Dierigl (CERN) |
| Abstract: | Symmetries are essential in our understanding of quantum systems. In recent years the concept of symmetries has been generalized to include higher-form symmetries (acting on extended objects), higher-group symmetries (mixing various higher-form symmetries), and non-invertible symmetries (which do not satisfy a group law). In this talk I will discuss the role of generalized symmetries and their breaking at the quantum level, via anomalies, in quantum gravity. In particular, I will highlight how topological charges carried by certain spacetime backgrounds can lead us to the prediction of new dynamical objects in the fundamental theory. Moreover, I will show that demanding the absence of (generalized) anomalies in the gauge sector imposes universal consistency conditions.
|
| Date: | Thu, 13.03.2025 |
| Time: | 17:00 |
| Duration: | 60 min |
| Location: | TU Wien: Wiedner Hauptstr. 8-10, yellow area, 10th floor, seminar room DB10E11 |
| Contact: | Daniel Grumiller, Ankit Aggarwal |
| SPECT- towards a new measurement of the free neutron lifetime in a full-3D magnetic trap |
| Speaker: | Martin Fertl (University of Mainz) |
| Abstract: | The high-precision determination of the free neutron lifetime n remains at the
forefront of low-energy particle physics. Neutron physics can provide a cornerstone
ingredient for a high-precision test of the Cabibbo-Kobayashi-Maskawa
(CKM) matrix unitarity without nuclear structure corrections. The matrix element
Vud can be extracted from the combination of an accurate, high-precision
determination of , the ratio of axial-vector and vector coupling strength of the
weak interaction, a commensurate theoretical description of neutron beta decay,
and a high-precision determination of n. The SPECT experiment has been in
operation at the ultracold neutron (UCN) source of the Paul Scherrer Institute
since 2023. Confining UCNs for thousands of seconds in a full 3D magnetic
gradient field trap, SPECT can extract n by counting the surviving UCN.
In a first step, SPECT aims to determine n wi |
| Date: | Fri, 14.03.2025 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Hartmut Abele |
|