Quarks, stars, Higgs bosons: the beginning of the universe.Cosmology and particle physics are closely connected and quantum physics can describe them on different energy scales: i.e. quantum fluctuations originating from the early phase of the universe are the seed for the formation of density fluctuations in the universe from which galaxies and stars emerged.
The current elementary particle theory, the so-called «Standard Model», is based on quantum physics and explains the masses of elementary particles through the «Higgs Mechanism». It also describes how protons and neutrons originate from quarks through the «strong interaction».
The countless riddles in cosmology lead to fascinating research fields examining questions like: Where does the matter-antimatter-asymmetry – a precondition to the occurence of the matter in the universe we are made of – originate from? What is the nature of «dark matter» and «dark energy»?
In order to find answers to these questions, we are developing the current «Standard Model» further in multiple directions. The questions are also linked to the understanding of the building blocks of matter: Is supersymmetry realised in nature? Are quarks divisible? How can gravity be incorporated into the «Standard Model» as a quantum theory? Our ultimate goal is to develop a unified theory of all elementary forces.
The main current interest is in the structure of hadrons and in particular in excited states of the nucleon. The study of hadronic and electromagnetic properties of excitations of the free nucleon, e.g. with meson photoproduction experiments, supplies the experimental basis for the development and test of modern hadron theories. The investigation of nucleons bound in nuclei is exploited to study the influence of the nuclear medium on the excitation modes.
Continuing a long and rich tradition of observational astronomy at the former Astronomical Institute of the University of Basel, our group is doing basic research in the fields of galactic and extragalactic astronomy. The focus of our research lies in the photometric study of dwarf galaxies in clusters of galaxies and in the nearby field. Dwarf galaxies are small but very important for many fields of astronomy, including cosmology and even particle physics. They are the most simple stellar systems and as such are ideally suited for studies of star formation and galaxy evolution. But the most prominent role played by dwarf galaxies is in the hunt for the elusive “dark matter”, whose existence but unknown nature is regarded as the hardest problem of astrophysics since decades. Our current project is a search for very faint, hitherto unknown dwarf galaxies in two southern nearby groups of galaxies in the constellations of Sculptor and Centaurus.
What is the theory of matter, forces and the universe? Stefan Antusch's group is working on the development of a more fundamental elementary particle theory which resolves the challenges of the present "Standard Model", gives rise to a consistent evolution of the universe and which can be tested by ongoing and future experiments. Towards this goal, the group currently focuses on particle theories of the early universe, unified theories of forces and the origin of particle masses and mixings, as well on ways to probe new physics with neutrinos.
Theoretical Nuclear Astrophysics activities range from nuclear physics issues (e.g. cross section predictions for strong and weak interaction processes and properties of nuclei far from stability) to numerical simulations of explosive astrophysical events (e.g. supernovae , X-ray bursts, and binary neutron star mergers). A major focus exists on nucleosynthesis contributions of these objects to galactic evolution.
Acroscopic phenomena in nature - in astrophysics and on Earth - often originate from the interaction of tightly coupled microscopic processes with different characteristic length and time scales. We develop efficient transport/hydrodynamics algorithms in the context of gravitational collapse and supernova explosions. A reliable numerical link between the input physics and the observables in distant astrophysical objects provides new information about matter under otherwise inaccessible conditions, or vice versa, allows the prediction of a large-scale evolution based on well-known input physics.