The aim of the EUSTRONG project is to investigate the Strong Interaction, one of the four fundamental forces of nature, in the universe. The Strong Interaction is responsible for holding neutrons and protons together in the atomic nucleus and for understanding the densest observable matter inside neutron stars. In addition, atomic nuclei play a key role in the detection of dark matter and in the study of the lightest neutrino particles. EUSTRONG will enable new discoveries in the physics of the Strong Interaction by developing innovative theories and methods.
The equation of state of dense nuclear matter, for example, sets the measure for the mass and size of neutron stars. At extreme densities beyond those achieved in atomic nuclei, astrophysical observations are particularly interesting. For example, information about the radius of neutron stars, which is sensitive to high densities, can be obtained from LIGO/Virgo observations of gravitational waves as neutron stars merge, as well as from new observations with NASA's NICER instrument on the International Space Station. "So far, this fits very well with our understanding about the equation of state of nuclear matter," explains Achim Schwenk. "With EUSTRONG, we now want to derive direct constraints on the interactions in dense matter from these astrophysical observations for the first time, and thus develop a unified description of matter in nuclei and stars."
Another milestone of the ERC project is the acceleration of many-body calculations with new emulation and network methods to enable systematic and global ab initio calculations based on the Strong Interaction for heavy nuclei. One focus is on extremely neutron-rich heavy nuclei (around neutron number 126), which play a central role in the formation of elements in the universe. The future accelerator facility FAIR (Facility for Antiproton and Ion Research) in Darmstadt will be a leader in this field. With the new developments, Achim Schwenk and his team then also want to investigate key nuclei that are used in extremely sensitive detectors to detect dark matter or are used for the discovery of coherent neutrino scattering, which was recently achieved for the first time. In the search for dark matter in the universe and new physics beyond the Standard Model, the Strong Interaction thus also plays an essential role.