Speaker
Description
A main goal of the HADES (High Acceptance Di-Electron Spectrometer) experiment at GSI is to study medium effects in e+e- production in heavy-ion reactions in the SIS-18 energy range (1-4 GeV/nucleon). Its excellent particle identification capabilities allowed for a systematic investigation of dielectron, strange particles and pion production in pion, proton, deuteron or heavy-ion induced reactions on proton or nucleus. The obtained dilepton spectra measured at various beam energies show important contributions from baryon resonance decays (R→Ne+e-) and a strong influence of the intermediate vector mesons (ρ/ω/φ) in the corresponding time-like electromagnetic form factors (eTFF).
In order to directly access such transitions, HADES has started a dedicated pion-nucleon program using the pion beam facility at GSI. For the first time, combined measurements of hadronic and dielectron final states have been performed in p-N reactions in the second resonance region, using polyethylene and carbon targets. Based on 2-pion production channels in p-p the baryon-meson couplings have been determined which are very crucial for the dilepton studies and finally the extraction of resonance Dalitz decay and eTFF.
The data collected with the carbon target have been used to study the pion and proton emission channels in various topologies (inclusive, pπ−, pπ+, pp, π+π−,..., ππpp). The interest is to provide information on the pion dynamics, which is crucial for dense hadronic matter studies using heavy-ion collisions at a few GeV/nucleon at GSI and later at FAIR. Results are compared to predictions of the INCL++ cascade and of transport models (SMASH, rQMD, GIBUU) providing a detailed test of the ingredients of these models.
