Study of baryonic resonances and ρ meson production in the reaction pp → ppπ+π- at 3.5 GeV with HADES

Abstract

The High Acceptance Di-Electron Spectrometer (HADES) installed at GSI in Darmstadt and de signed to investigate dielectron production in heavy-ion collisions in the range of kinetic beam energies 1-3 A GeV is also an excellent detector for charged hadron detection. We discuss the analysis of the pp → ppπ+π- channel at an incident energy of 3.5 GeV, using results from pp→ppπ0, pp→pnπ+ and pp → pKΛ measured at the same energy by HADES. A consistent description of the differential cross sections as a function of the invariant mass and the production angles is achieved by a simple resonance model taking into account the single and the double excitation of baryonic resonances with masses up to 1.9 GeV. The contributions can be quantified and confronted to the inputs of transport models or to the predictions of dedicated models for nucleon-nucleon reactions. In addition, using specific kinematical cuts, the total production cross section and the angular dis tribution of the ρ meson have been also extracted. As both baryon resonances and the ρ meson are important sources of di-electrons, these results will provide valuable constraints for the interpretation of the dielectron spectra measured by the HADES collaboration.