Monday, 22 April 2024
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13:00 |
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SFB1225 ISOQUANT |
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Jörg Jaeckel |
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Lunch Seminar: Oscillations in the Cosmos and in the Lab From axion dark matter to things that are not even particles |
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Institut für Theoretische Physik, PI, Goldene Box & Online via Zoom |
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In this talk we start with the classical example of an oscillating cosmological field axion and axion-like particle dark matter. We will see that it is a suitable dark matter candidate, albeit one with interesting wave-like features that express themselves as coherent oscillations. We discuss existing and future probes of this type of dark matter. Following the theme of probing tiny oscillations we go beyond dark matter and even beyond particles and ask whether there could be a fundamental violation of Poincare invariance and study tests of this fundamental symmetry by looking for time-varying and oscillating effects. |
Tuesday, 23 April 2024
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14:15 |
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Kosmologie und Elementarteilchenphysik |
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Ziyang Zheng |
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Model-independent test on the cosmological Poisson equation |
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Institut für Theoretische Physik, Phil12, SR106 |
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The theory of gravity holds significant importance in our understanding of the large-scale structure and dynamics of the Universe. We first demonstrate how one can measure the gravitational slip, η, in a model-independent way by combining observations from galaxy clustering and weak lensing. Additionally, we propose a method to test the cosmological Poisson equation model-independently while maintaining independence from specific models for the background expansion, the power spectrum shape, and the non-linear corrections. We show that one can only measure the combination Μ≡Ω{m,0}μ, where μ quantifies the deviation of the Poisson equation from the standard one and Ω{m,0} is the present matter density fraction. We also obtain constraints on M for a survey that approximates a combination of the Dark Energy Spectroscopic Instrument and Euclid by employing a recent model-independent forecast for the growth rate f and the expansion rate E. |
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16:30 |
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Heidelberg Joint Astronomical Colloquium |
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Dr. Laurent Eyer |
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The Gaia mission: an exceptional astrometric, photometric and spectroscopic multi-epoch survey |
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Philosophenweg 12, Grand Lecture Room |
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At the core of the ESA Gaia mission lies a comprehensive multi-epoch survey, with astrometric, photometric, spectrophotometric, and spectroscopic measurements of the entire sky. The astrometric time series provide parallax and proper motion, also impacting astrometric binary stars, and the detection of black holes and exoplanets. The photometric measurements allow us to describe the star properties and their variability in an unprecedented manner, leading to many records and impacting the distance scale. The radial velocity breaks also observational records and allows us to improve and complete the description of binaries and kinematic properties of the Milky Way. The breadth of the results of Gaia is so wide that it is nearly impossible to summarize all its aspects. I will give a review of (biased) selected topics. Those unable to attend the colloquium in person are invited to participate online through Zoom (Meeting ID: 942 0262 2849, passcode 792771) using the link: https://eu02web.zoom-x.de/j/94202622849?pwd=dGlPQXBiUytzY1M2UE5oUDRhbzNOZz09 During his visit to Heidelberg, Professor Eyer will be available for meetings by arrangement with his hosts, Saskia Hekker (saskia.hekker@h-its.org) and Michael Bazot (michael.bazot@h-its.org) |
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17:00 |
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Particle Colloquium |
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Prof. Bjoern Penning |
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Searching for Dark Matter High and Low |
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Physikalisches Institut INF 226, Konferenzraum 1-3 (Room 00.101 bis 00.103) |
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Wednesday, 24 April 2024
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09:30 |
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Seminar Dynamik und Struktur von Atomen und Molekülen |
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Arikta Saha; Excited atoms and molecules in strong fields |
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Time-resolved helium plasma dynamics using XUV transient absorption spectroscopy |
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Bothe seminar room, Bothe laboratory |
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17:00 |
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Zentrum für Quantendynamik Kolloquium |
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Prof. Dr. Giovanna Morigi |
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tba |
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SFB1225 ISOQUANT |
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Kathryn Kreckel |
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Meet&Mingle@ISOQUANT (mentoring & networking for FLINTA* students in physics): meet the working group of Kathryn Kreckel |
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Institut für Theoretische Physik, PI, seminar box 1st floor |
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tba |
Thursday, 25 April 2024
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11:15 |
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Teekolloquium |
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Prof. Matthias Neubert |
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Weakly-coupled light new physics |
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Grosser Hoersaal/Big Lecture Hall (library) |
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The existence of light, weakly-interacting new particles beyond the Standard Model is a well-motivated alternative to new particles existing at the TeV scale or beyond. With the example of axion-like particles (ALPs), which offer an explanation of the puzzling absence of the electric dipole moment of the neutron, we discuss the current status of both direct searches at the LHC and in flavor experiments, and indirect searches using precision measurements of electroweak and low-energy observables. We emphasize the importance of subtle quantum effects, which generate multiple ALP couplings to the Standard Model particles even if at a high scale only a single ALP coupling is non-vanishing. |
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ARI Institute Colloquium |
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Kathryn Kreckel |
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The Local Volume Mapper (LVM): Physics at the energy injection scale |
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ARI, Moenchhofstrasse 12-14, Seminarraum 1.OG |
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I will present an overview of the Sloan Digital Sky Survey V (SDSS-V) Local Volume Mapper (LVM), which began survey operations last November. The LVM is a new optical integral-field spectroscopic survey of the Milky Way (at
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16:15 |
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Teilchen-Tee |
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Felix Kahlhöfer |
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Resonant, asymmetric or inelastic? The status of sub-GeV dark matter (Pre-talk 15:30) |
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Institut für Theoretische Physik, Phil12, SR106 |
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Sub-GeV dark matter particles produced via thermal freeze-out evade many of the strong constraints on heavier dark matter candidates. At the same time these particles face a multitude of new constraints from laboratory experiments, astrophysical observations and cosmological data. In my talk, I will review these constraints and the various ways how they can be satisfied. A particular focus is on models that systematically evade the very strong bounds on the annihilation rate of sub-GeV dark matter particles. I will present results from various global fits of these models, which not only determine the viable parameter regions, but also quantify the necessary fine tuning and allow for Bayesian model comparison. I will also discuss models that predict new signals that can be targeted with dedicated analyses in laboratory experiments and evaluate the discovery prospects of near-future experiments. |
Friday, 26 April 2024
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17:00 |
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Physikalisches Kolloquium |
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Prof. Dr. Gregor Kasieczka |
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The road to AI-based discovery in particle physics |
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KIP, INF 227, Hörsaal 1 |
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Modern machine learning and artificial intelligence are starting to fundamentally change how we analyze huge volumes of data in particle physics and adjacent scientific disciplines. These breakthroughs promise new insights into major scientific questions such as the nature of dark matter or the existence of physical phenomena beyond the standard model. This colloquium will provide an overview of recent, exciting developments with a focus on model agnostic discovery strategies  including first experimental results, fast simulations, and foundation models that simultaneously solve multiple tasks across multiple datasets. |
Monday, 29 April 2024
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16:30 |
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Particle and Astroparticle Theory Seminar |
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Prof. Qaisar Shafi (Delaware) |
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Monopoles, Strings and Gravitational Waves |
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Seminar room Lindner 339, Gentner lab, 2nd floor |
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A variety of interesting topological objects arise in spontaneously broken unified theories. They include monopoles and strings as well as more complex structures with
cosmological implications. In this talk I will discuss primordial magnetic monopoles, cosmic strings and gravitational waves. |
Tuesday, 30 April 2024
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11:15 |
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Seminar Theoretische Quantendynamik |
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Dr. Pei-Lun He, MPIK |
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Photoelectron Polarization Vortexes in Strong-Field Ionization |
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Otto Hahn lecture hall, library building |
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Abstract: //
The spin polarization of photoelectrons induced by an intense linearly polarized laser field is investigated using numerical solutions of the time-dependent Schrödinger equation in companion with our analytic treatment via the spin-resolved strong-field approximation and classical trajectory Monte Carlo simulations. We demonstrate that, even though the total polarization vanishes upon averaging over the photoelectron momentum, momentum-resolved spin polarization is significant, typically exhibiting a vortex structure relative to the laser polarization axis. The polarization arises from the transfer of spin-orbital coupling in the bound state to the spin-correlated quantum orbits in the continuum. The rescattering of photoelectrons at the atomic core plays an important role in forming the polarization vortex structure, while there is no significant effect of the spin-orbit coupling during the continuum dynamics. Furthermore, spin-polarized electron holography is demonstrated, feasible for extracting fine structural information about the atom. |
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14:15 |
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Kosmologie und Elementarteilchenphysik |
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Alexander Ganz |
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Exploring Minimally Modified Gravity |
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Institut für Theoretische Physik, Phil12, SR106 |
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Minimally modified gravity models are a class of modified gravity theories with only two local degrees of freedom as in General Relativity. In this seminar I want to discuss their general properties such as the existence of a preferred foliation and then discuss phenomenological applications in the early Universe. While during inflation the modifications to the power spectra are slow-roll suppressed, for the bispectrum we can get new signatures deviating from standard single scalar field models. Further, I will discuss how these models can be used to construct stable and viable bouncing scenarios. |
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16:30 |
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Heidelberg Joint Astronomical Colloquium |
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Dr Mario Flock |
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Rim Worlds: Computational astrophysics of accretion disks |
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Philosophenweg 12, Main Lecture hall (gHS) |
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Abstract to be announced Those unable to attend the colloquium in person are invited to participate online through Zoom (Meeting ID: 942 0262 2849, passcode 792771) using the link: https://eu02web.zoom-x.de/j/94202622849?pwd=dGlPQXBiUytzY1M2UE5oUDRhbzNOZz09 |
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17:00 |
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Particle Colloquium |
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Giovanni Dal Maso |
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Latest Results from MEG2 |
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Physikalisches Institut INF 226, Konferenzraum 1-3 (Room 00.101 bis 00.103) |
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Thursday, 2 May 2024
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11:15 |
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Teekolloquium |
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Dr Christoph Wiesinger |
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Probing the neutrino mass with KATRIN and ultra-low background X-ray detectors for IAXO |
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Grosser Hoersaal/Big Lecture Hall (library) |
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Our understanding of fundamental particles is incomplete. The absolute neutrino mass remains unknown and strong interactions appear suspiciously symmetric, hinting at the existence of axions. KATRIN performs precision spectroscopy of tritium beta-decay electrons, probing the effective electron anti-neutrino mass with unprecedented sensitivity. IAXO is a next-generation helioscope aiming to detect solar axions, as they are converted into X-rays along a strong magnet pointing towards the sun. In my presentation, I will discuss the challenging analysis of the first five KATRIN neutrino mass campaigns and the potential of ultra-low background semiconductor detectors, based on the TRISTAN upgrade of KATRIN, to boost the search for solar axions with IAXO. |
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ARI Institute Colloquium |
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Francesco Flammini Dotti |
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Massless objects dynamics in star clusters |
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ARI, Moenchhofstrasse 12-14, Seminarraum 1.OG |
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The dynamical evolution of massless objects in star clusters aims to explore their dynamics during the dynamical evolution of such structures, which is not easy observable in star clusters, and still not possible in dense star clusters such as globular clusters. In a star cluster, the main phenomenon we are going to focus on are the mass segregation and core collapse. I will first introduce previous works that looked into the motion of these objects, and then I will numerically explore the dynamical evolution of such objects, varying the number density of the hosting star cluster. As a final point, I will try to confute if the relative large abundance of free-floating planets in our galaxy is due to their ejected free-floating planets. I will use NBODY6++GPU-ML (a N-body code which performs simulations with a large number of particles and massless particles, i.e., star clusters with free-floating planets). The results pinpoint how the massless particles are not particularly affected by mass segregation, but only by the central gravitational evolution of the core of the star cluster, suggesting that those particles, in relatively dense star clusters, are ejected only at much larger timescales. |
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16:15 |
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Teilchen-Tee |
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Wilke van der Schee |
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Bayesian analysis of heavy ion collisions (Pre-talk 15:30) |
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Institut für Theoretische Physik, Phil12, SR106 |
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TBA |
Friday, 3 May 2024
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17:00 |
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Physikalisches Kolloquium |
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Prof. Dr. Elena Hassinger |
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Odd ways to unconventional superconductivity |
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KIP, INF 227, Hörsaal 1 |
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Superconductivity is a fascinating state of matter that transforms metals at very low temperature into perfect conductors and perfect diamagnets. This enables numerous technical applications for magnetic levitation, electric current transport without loss and for quantum information technology. A desired but rare type of unconventional superconductivity with possible uses in topological quantum computing is one where the superconducting condensate is odd under inversion symmetry, so-called odd-parity superconductivity. Only a handful of uranium-based materials have this property and it is usually explained by the presence of ferromagnetism enforcing a parallel alignment of the electrons forming the Cooper pair. In the colloquium talk I will present our astonishing discovery that superconductivity in the material CeRh2As2 with a critical temperature of only 0.4 kelvin switches its state in a magnetic field and is then stable up to the extreme magnetic field of 16 tesla. The switching is understood as a unique phase transition from even-parity to odd-parity superconductivity that likely relies on a special crystallographic feature of the underlying material, CeRh2As2, and not on ferromagnetic interactions. I will show our experimental investigations into the question what stabilises such a transition that we address by tuning superconductivity and other coexisting orders with temperature, magnetic field and hydrostatic pressure. The resulting knowledge paves the way for the design of other odd-parity superconductors with higher transition temperatures useful for applications. |
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