Hades experiment probing baryonic matter at SIS18 overview of results

HADES experiment at GSI is the only high precision experiment probing nuclear matter in the beam energy range of a few AGeV. Pion, proton and ion beams are used to study rare dielectron and strangeness probes to diagnose properties of strongly interacting matter in this energy regime. Selected results from p + A and A + A collisions are presented and discussed. We find that ρ meson production in our energy range is strongly affected by a strong coupling to low-mass baryonic resonances which is reflected in a significant broadening of the meson mass distribution visible in p + A and A + A reactions. Particularly, results from A + A demonstrate a significant contribution from the dense phase of the collisions which can be successfully described by a thermal radiation from the in-medium? in agreement with the higher energy data. Studies of the ω production off nucleus show a strong absorption of the meson in nuclear matter in accordance with the results from photon induced reactions. The ω and φ signals have also been reconstructed in Ar + KCl collisions at energies below the N - N production threshold. A surprisingly large R_φ-/-ω production ratio (more than one order of magnitude larger than in N + N collisions) has been found, indicating no suppression for the φ production and consequently a significant contribution to the K^- production