Johannes Gutenberg University Mainz > Faculty 08 > Physics > Physics Research > Research Areas > Astro-, Astroparticle & Neutrino Physics
Neutrinos are the strangers of the Standard Model. Interacting only weakly with the other particles, a number of key properties of neutrinos are still unknown—including their tiny masses and how these are generated. While Project 8 aims to measure the absolute value of their masses directly, the JUNO and IceCube experiments aim to determine their ordering. One possible mechanism explaining the smallness of the neutrino masses predicts that neutrinos would be their own antiparticles. This would give rise to the phenomenon of neutrinoless double beta decay researched by the NuDoubt⁺⁺ collaboration. More generally, neutrinos and anti-neutrinos could behave differently. This is commonly described by a CP-violating phase which can be observed when comparing neutrino- and anti-neutrino beams at DUNE. Technological development for future experiments and cross-section measurements for accelerator neutrinos are the focus of the ANNIE experiment at Fermilab.
Neutrinos also provide a unique avenue for theoretical research. We explore the origin of their masses, non-standard neutrino interactions, and their possible role in the generation of the matter-antimatter asymmetry (groups of Prof. Harz and Prof. Kopp). Despite many open questions about their properties and origins, neutrinos can serve as cosmic messengers, carrying information from a wide range of astrophysical objects—including the Earth, the Sun, and distant cosmic sources.
The early universe, from the Big Bang to the formation of galaxies and stars, holds the key to several unresolved fundamental questions in physics. These include the dynamics of inflation, the origin of the matter-antimatter asymmetry, and the nature and production of dark matter. Insights into this epoch are gained from observations of the cosmic microwave background, large-scale structures, and, increasingly, from gravitational wave searches.
Our research addresses these profound questions through a variety of approaches. We study mechanisms such as baryogenesis and leptogenesis to explain the origin of the matter-antimatter asymmetry. We investigate phase transitions and the dynamics of the dark sector, which give rise to gravitational waves and other observational probes of the early universe. We also examine inflationary dynamics followed by the (p)reheating of the universe, explore candidates for dark matter, and advance the theoretical foundations of early universe cosmology using quantum field theory in curved spacetime and non-equilibrium quantum field theory. In doing so, we forge strong links between high-energy physics and cosmological observations. On the experimental side, the GravNET experiment will search for gravitational waves at GigaHertz frequencies, with the ultimate goal of probing the early Universe shortly after the end of Inflation and reheating. Complementary probes of the physics of the early universe are pursued in high energy particle physics, including in particular the study of Higgs physics in the context of the electroweak phase transition and quark and lepton flavour physics as a key ingredient of baryogenesis.
Astrophysical observations provide overwhelming evidence for the existence of an additional non-luminous matter component in our universe, commonly known as dark matter. Little is known, however, about its properties. In fact, its mass is virtually unconstrained, ranging from ultralight scalar fields with masses much lighter than the neutrinos up to primordial black holes with many times the mass of the sun. Determining the nature of dark matter is therefore one of the key open questions in astro-particle physics.
In Mainz, the CASPEr and GNOME experiments search for ultralight dark matter using highly sensitive spin precession devices and optical magnetometers (group of Dmitry Budker). The XENON experiment searches for collisions of GeV- to TeV-scale dark matter particles with Xenon atoms in a highly shielded underground experiment. The COSI Compton telescope, a satellite to be launched in 2027, will search for gamma-ray emissions from MeV-scale dark matter. Theory groups in Mainz are developing and analyzing new models of dark matter, advancing methods for the theoretical prediction of dark matter abundance and its interactions, and devising novel strategies to search for dark matter. This effort is complemented by collider searches for dark matter particles or their mediators at the MESA accelerator in Mainz as well as within the ATLAS collaboration, see here.
How do stars create elements, and what happens to matter under the most extreme conditions in the universe? How are elements forged in our Milky Way? What happens in a supernova explosion? Our research explores these questions by carrying out experiments in the sky and in the laboratory. Our studies on stellar nucleosynthesis and the structure of neutron stars combinines cutting-edge experiments with theoretical modeling. At the high-intensity accelerator MESA, we investigate nuclear reactions essential for understanding how elements form in stars. At the same time, we are exploring the properties of neutron-rich matter to better understand the behavior of matter under extreme densities and the physics shaping neutron stars. The Compton Spectrometer and Imager (COSI) is a satellite mission designed to study stellar physics, specifically focusing on gamma-ray emissions from radioactive isotopes produced in supernovae and the origin of positrons in our galaxy.
