The High Acceptance Di-Electron Spectrometer (HADES) is designed specifically to detect electrons and positrons from heavy ion and hadron (pion, proton) collisions. In our analysis, these single leptons are identified using state-of-the-art techniques involving artificial intelligence and machine learning. Leptons are matched into respective dilepton pairs. They can be investigated in a variety of ways but a major focus is set to reconstruct the invariant mass spectra. Dilepton invariant-mass spectra are the only observable which gives direct access to the in-medium modification of hadronic spectral functions. Using simulations as well as information about other measured particles, e.g. pions, one can further correct and isolate the invariant mass spectrum to only represent dileptons coming from the hottest and densest phase of the collision. The significant excess radiation of dileptons, beyond final-state hadron decays, can be seen in Figure 2. It can be isolated by subtracting the hadronic cocktail from the data. The resulting spectrum shown in Fig.3 allows to extract important physics: microscopic properties of the hot and dense medium, its life time and temperature, its collective expansion dynamics or its transport properties.
We are analysing dielectron data from heavy-ion collisions (Au+Au, Ag+Ag) as well as from elementary collisions (proton, pion beams impinging on proton or heavy target).
. Publication list of the HADES collaboration on inSPIRE