This seminar explores the evolving field of fractons, quasiparticles with limited mobility, and their relationship with elasticity. Mechanical properties of crystals on curved substrates mix elastic, geometric and topological degrees of freedom. In order to elucidate properties of such crystals I formulate the low-energy effective action that combines metric degrees of freedom with...
This talk covers several recent developments in the physics of dense QCD with an emphasis on the impact of multiple phase transitions on astrophysical manifestations of compact stars. It is conjectured that pair-correlated quark matter in β-equilibrium is within the same universality class as spin-imbalanced cold atoms and the isospin asymmetrical nucleonic matter. This then implies the...
We apply large-scale molecular dynamics simulations based on density functional theory (DFT-MD) to infer the high-pressure phase diagram of hydrogen-helium and H-C-N-O mixtures. Of particular interest is the nonmetal-to-metal transition in dense fluid hydrogen that occurs at few megabars (metallization). Furthermore, demixing of hydrogen and helium is predicted at about the same extreme...
With the advent of advanced laser systems producing high-frequency X-ray beams, e.g. the EuropeanXFEL as a prominent example, a regime of laser-plasma interaction is reached, where all-optical methods, as used in particle-in-cell simulations, are no longer applicable. Instead, the interaction of hot electrons and the X-ray laser pulse needs to be modeled with a QED-driven approach....
Fast and accurate equation-of-state (EOS) data is of critical importance in the warm dense matter regime, for example as input to hydrodynamic codes used in inertial confinement fusion modelling. Since EOS data must be generated on-the-fly for many applications, a tabular approach based on interpolation of known data points is generally used. Alternatively, average-atom models are (in some...
Dense hydrogen is important because of its ubiquitous presence in the universe, its technological applications and its suitability for developing and testing ab initio simulation methods. Even though it is the “holy grail” of high pressure research, its phase diagram above 100 GPa is uncertain. We have made a new study of its phase diagram using a machine-learned interatomic potential...
In ultra-strong electric fields energy can be converted into electrons and positrons. We introduce a novel approach to calculate the mean particle number in collisions of short-pulsed laser fields. In this regard, we further discuss the different regimes of pair production in terms of their unique signatures in particle phase-space and identify the relevant time scales regarding particle...
Astrophysical simulations are crucial for investigating high baryon density environments and exploring the occurrence of a first-order QCD hadron-quark matter phase transition under extreme conditions. Specifically, multi-messenger neutrino and gravitational wave emissions from corecollapse supernovae not only provide a measurable signal for the presence of deconfined quark matter, but also...
The presentation will begin with a concise introduction to Quantum Electrodynamics (QED) in the presence of external background fields, offering insights into the fundamental interactions between matter and electromagnetic fields. Following this, we will delve into the significance of light-by-light scattering in QED, examining ist amplitude (also known as the four-photon amplitude) with...
The first detection of gravitational waves form a neutron star merger some years ago has highlighted the prospects of inferring properties of high-density matter from these spectacular astrophysical events. In particular, the postmerger phase represents an environment of hot and dense matter implying that the different observables from this phase carry valuable information. We will provide an...
