Measurement of the +(1385) in elementary collisions

The study of rare resonances with strange content produced in p+p and p+Nb collisions at 3.5 GeV kinetic energy has recently been addressed by the HADES collaboration at GSI. Here we present the results obtained for the Σ(1385) resonance produced in p+p collisions at 3.5 GeV. The spectral function and the differential cross-section of the resonance could be evaluated. With a nominal mass of 1385 MeV/c and a width of about 40 MeV/c, this rather broad resonance is lying close to the Λ(1405) in the mass spectrum. The study of the Λ(1405) is of great importance to understand quantitatively the the Kaon-Nucleon interaction [1], and the detailed knowledge of the Σ(1385) line shape is a prerequisite to extract a clean signature of the Λ(1405). Furthermore, the Σ(1385) resonance can be utilized to approach the topic of in-medium properties of baryonic resonances. The knowledge of the resonance properties in a low-density and finite-temperature environment is a prerequisite to interpret the experimental results obtained for proton-nucleus and heavy-ion collisions. A total statistics of 1.2·109 p+p collisions with a kinetic energy of 3.5 GeV have been collected with the HADES spectrometer at GSI. The following semi-exclusive reaction, which includes a non detectable neutron, has been selected from the available statistics: