Prof. Luca Argenti, Theoretical Attosecond Group, Department of Physics & CREOL, University of Central Florida
Two-photon double ionization of atoms and molecules with a finite-pulse virtual sequential model
Central Seminar Room, library building
14:20
Special Seminar
Felipe Kalluf Faria, Theoretical Attosecond Group, Department of Physics and CREOL, University of Central Florida
Branching ratios and ATI spectra of helium doubly excited states
Central Seminar Room, library building
14:30
Special Seminar
Nicholas Lewis, Theoretical Attosecond Group, Department of Physics & CREOL, University of Central Florida
Computing charge migration with the ASTRA code
Central Seminar Room, library building
14:40
Special Seminar
Andrew Short, Theoretical Attosecond Group, Department of Physics & CREOL, University of Central Florida
Attosecond optical and photoelectron spectra of 02
Central Seminar Room, library building
14:50
Special Seminar
Julian Jakob, Zentrum für Optische Technologien, Hochschule Aalen
Extracting RABBITT-like phase information from time-dependent transient absorption spectra
Central Seminar Room, library building
Tuesday, 15 July 2025
09:00
Workshop
Prof. Dr. Anne Harth, Hochschule Aalen
Teaching as a young scientist
Central Seminar Room, library building
11:15
Seminar Theoretische Quantendynamik
Ingmar Kloß, MPIK
Geometrical reconstruction of Dirac solutions: gravitational interactions and comparison to electromagnetic case
Seminar room 242, Bothe Lab
14:15
Kosmologie und Elementarteilchenphysik
Mariateresa Crosta
Gravitational Astrometry as a Local Cosmology Laboratory
Institut für Theoretische Physik, Online
The ancient astronomical pursuit of measuring star positions and motions is now shaped by Einstein's theory. High-precision space astrometry, pioneered by ESA's Gaia satellite, is pushing fundamental astronomy beyond the classical Newtonian paradigm into Einstein's General Relativity, the current standard theory of gravity. This unprecedented accuracy demands a full general relativistic analysis of photon trajectories, moving beyond simple straight lines to a sophisticated relativistic measurement toolkit. Consequently, Gaia's highly accurate measurements must integrate relativistic astrometry directly into the core of data analysis to ensure the quality of scientific findings. These advanced models offer a consistent interpretation of General Relativity's observables for reconstructing the Milky Way. Gravitational astrometry creates a unique opportunity to test the Milky Way's role in gravity theories, establishing a coherent framework to probe our entire Galaxy as a product of cosmological evolution. This effectively forms a Local Cosmology laboratory, allowing us to explore the relationships between baryonic structures (and their evolution) and the Universe's dark components, while also providing template models for other similar galaxies. We present the first application of Gaia's precise relativistic kinematics to trace the Milky Way's rotation curves. Our latest results compare an exact general relativistic approach with the (Lambda)CDM and MOND models, using nearly one million Gaia-only sources selected for accurate 6-dimensional phase-space reconstruction. Likelihood analysis shows these models are equally consistent with the data, validating a relativistic model for the Milky Way. Our findings provide, for the first time, quantitative evidence that gravitational dragging, as derived from Einstein's field solution, could mimic Âdark matter or MOND effects for the observed flatness of the Galactic rotational curve, implying that no additional non-baryonic matter is necessarily required. Moreover, gravitational astrometry offers new techniques to observe tiny spacetime variations caused by interposed masses or passing gravitational waves. Gaia's extensive decade-plus observations can help identify faint gravitational signatures in raw astrometric data, enhancing synergies with gravitational wave detectors and pulsar timing arrays.
16:30
Heidelberg Joint Astronomical Colloquium
Pablo Marchant
From mass transfer to stripped stars
Binary interactions shape the evolution of the most massive stars, leading to significant deviations from the evolutionary pathways possible in single star evolution. These processes impact the universe at large scales and result in high energy events such as peculiar supernovae and gravitational wave sources. To understand these outcomes, it is important to assess binary evolution in early stages ranging from pre-interaction, roche-lobe overflow and post-interaction phases. I will discuss the current progress in our understanding of mass-transferring binaries, covering the impact of this process on the donor star (with the possible production of a stripped star), as well as the response of its companion. Of particular importance in recent years is the identification of bloated stripped stars caught immediately after interaction which provides a snapshot of the end-states of mass transfer, and I will discuss how their properties constrain orbital evolution and the efficiency of mass transfer. I will also emphasize that many of the uncertain processes in massive binary star evolution can also be assessed through the study of intermediate mass systems, for which the physics in early evolutionary phases does not differ significantly. To arrange a visit with the speaker during the visit, please contact their host: Jaime Villaseñor (MPIA)
17:00
Particle Colloquium
Prof. Dr. Ulrich Uwer
The LHCb Phase-2b upgrade
Physikalisches Institut INF 226, Konferenzraum 1-3 (Room 00.101 bis 00.103)
Wednesday, 16 July 2025
09:30
Oberseminar Mathematische Physik
Jakob Geisler
Almost Commuting Self-Adjoint Operators and Iterated Commutator Estimates
Institut für Theoretische Physik, Phil19
Given two almost commuting self-adjoint operators, a new method for finding exactly commuting operators is presented. For this, a differential equation for self-adjoint Hilbert-Schmidt operators is introduced. Quantitative results are proven that the exactly commuting operators are close to the old ones in the Hilbert-Schmidt norm. The proof relies on a novel estimate in which the norm of the commutator is bounded from above by the norm of the iterated commutators times a constant. This inequality is proven in finite dimensions and lower bounds for the optimal constants are given.
17:00
SFB1225 ISOQUANT
Prof. Dr. Frauke Gräter
Meet&Mingle@ISOQUANT: Networking and Mentoring platform for FLINTA* students in physics
Institut für Theoretische Physik, PI, Goldene Box
tba
Thursday, 17 July 2025
11:15
Teekolloquium
Prof. Wim Ubachs
Molecular hydrogen at the heart of physics
Grosser Hoersaal/Big Lecture Hall (library)
Hydrogen in atomic and molecular form, including the deuterium and tritium isotopes, is key in astrophysics, as well as in stellar and man-made fusion. Hydrogen has become a benchmark system for testing theory at the most fundamental level and for probing physics beyond the Standard Model: are there forces beyond the three included in the Standard Model of physics plus gravity, and are there just 3+1 dimensions. Comparison of laboratory wavelengths of transitions in hydrogen may be compared with the lines observed during the epoch of the early Universe to verify whether fundamental constants of Nature have varied over cosmological time. In recent studies dissociation limits of H2, HD and D2 are measured to 10-digit accuracy. Currently vibrational transitions are being measured via sensitive cavity-enhanced techniques, also for the radio-active HT molecule. In H2 record-high sensitivity is achieved for probing a quadrupole transition in saturation.
ARI Institute Colloquium
Anna Saburova
On the enigmatic beasts - giant low surface brightness galaxies
ARI, Moenchhofstrasse 12-14, Seminarraum 1.OG
Giant low surface brightness galaxies (gLSBGs) have the largest discs in the Universe with the radii up to 130 kpc. The formation of such enormous discs is a stress-test for the hierarchical galaxy formation paradigm and without clarifying it we cannot paint a coherent picture of galaxy evolution. In the talk I will give the answers to the following questions. How rare are gLSBGs? What are the formation scenarios of gLSBGs? And how does it all correspond to the results of modern cosmological simulations? These answers are based on both in-depth study of 8 gLSBGs, including the results of our deep spectroscopic and photometric observations, HI data collected in the framework of our observing programs and complemented by archival datasets. Finally, we used deep optical images from HSC Subaru Strategic Program and publicly available redshift catalogs, estimated the volume density of gLSBGs in the local Universe and compared it to state-of- the-art numerical simulations.
16:15
Teilchen-Tee
Clare Burrage
The Hunt for Light Scalar Fields
Institut für Theoretische Physik, Phil12, SR106
In this talk I will focus on the introduction of new light scalar fields which have been suggested as possible explanations for dark matter and the accelerated expansion of the universe. I will show examples of the unusual phenomenology that can arise in such theories, and explain why properties of macroscopic objects, such as density and compactness, are important in understanding how to detect them. I'll then show how this leads to new opportunities for precision laboratory measurements to shed light on this type of new physics, and discuss the challenges of accurately simulating their behaviour.
16:30
Special Seminar
Prof. Sivarama Krishnan; Indian Institute of Technology Madras
Interatomic Coulombic decay processes in He nanodroplets - what we do and what we don't (yet) understand
Seminar room, Bothe Lab
Friday, 18 July 2025
17:00
Physikalisches Kolloquium
Prof. Ralph Keeling
Perspectives on modern climate change from 67 years of direct atmospheric measurements
Perspectives on modern climate change from 67 years of direct atmospheric measurements Prof. Ralph Keeling GEOSCIENCES RESEARCH DIV., Scripps Institution of Oceanography, UC San Diego At the forefront of modern climate change research are time-series observations of atmospheric CO? and related species, such as atmospheric O?. These records now span many decades, providing unequivocal evidence of the profound influence of humans on the planetÂparticularly through the burning of fossil fuels. This talk will chart the history of this field, from the early measurements and scientific puzzles to the ongoing challenges of mitigating and adapting to climate change.
Tuesday, 22 July 2025
14:15
Kosmologie und Elementarteilchenphysik
Andrea Lapi
Little Ado About Everything: \eta CDM, a stochastic cosmology from structure formation
Institut für Theoretische Physik, Online
I will present the eta CDM framework, a new cosmological model aimed to cure some drawbacks of the standard Lambda CDM scenario, such as the origin of the accelerated expansion at late times, the cosmic tensions, and the violation of the cosmological principle due to the progressive development of inhomogeneous/anisotropic conditions in the late Universe via structure formation. To this purpose, the model adopts a statistical perspective envisaging a stochastic evolution of large-scale patches in the Universe, which is meant to render our ignorance on the complex processes leading to the formation of the cosmic web. The stochasticity among different patches is technically described via the diverse realizations of a multiplicative noise term (Âa little adoÂ) in the cosmological equations, and the overall background evolution of the Universe is then operationally defined as an average over the patch ensemble. I will highlight that the ensemble-averaged evolution in eta CDM can be described in terms of a spatially flat cosmology and of an Âemergent dark energy with a time-dependent equation of state, able to originate the cosmic acceleration with the right timing and to solve the coincidence problem. I will showcase the extremely good performances of the eta CDM model in confronting the most recent supernova type-Ia, baryon acoustic oscillations and structure growth rate datasets. I will stress that eta CDM is able to alleviate simultaneously both the H0 and the f sigma 8 tensions. Finally, I will propose that the Linders diagnostic test may constitute a helpful tool to better distinguish eta CDM from the standard scenario in the near future via upcoming galaxy surveys at intermediate redshifts such as those being conducted by the Euclid mission.
16:30
Heidelberg Joint Astronomical Colloquium
Timothy Davis
Tracing out the darkness with cold gas: dynamically probing galaxy evolution and black holes
To arrange a visit with the speaker during the visit, please contact their host: Dominika Wylezalek
17:00
Particle Colloquium
Prof. Dr. Marc Schumann
Dark Matter and more with XENONnT and XLZD\n
Physikalisches Institut INF 226, Konferenzraum 1-3 (Room 00.101 bis 00.103)
Wednesday, 23 July 2025
09:30
Seminar Dynamik und Struktur von Atomen und Molekülen
André Giraldi; Ultra-cold dynamics and collisions
Towards experimental studies of Interatomic Coulombic Electron Capture
Central Seminar Room, library building
16:30
Zentrum für Quantendynamik Kolloquium
Prof. Zoran Hadzibabic
tba
Physikalisches Institut, INF 226, K 1-3
Thursday, 24 July 2025
11:15
ARI Institute Colloquium
Rainer Spurzem
DRAGON star cluster simulations and how to form an intermediate mass black hole
ARI, Moenchhofstrasse 12-14, Seminarraum 1.OG
DRAGON star cluster simulations have provided the first fully realistic long-term simulations of globular star clusters, have reproduced LIGO/Virgo observed binary black hole mergers, and are now entering into the next phase to simulate more massive, young and nuclear star clusters. They are based on the direct N-body simulation code Nbody6++GPU. In the talk an introduction and overview to direct N-body simulation and DRAGON simulations is given. Two current new applications are then shown, first initially very dense star clusters which form quickly an intermediate mass black hole of order 50.000 solar masses, which could be a seed for massive black holes in the early universe. Second, a still ongoing project is discussed, in which an already pre-existing supermassive black hole in a nuclear star cluster is followed, how it tidally disrupts stars, and captures low-mass stars, white dwarfs, neutron stars and stellar mass black holes.
