The High Acceptance DiElectron Spectrometer HADES has been recently commissioned at GSI, Darmstadt. It has been designed for systematic studies of hadron properties inside nuclear matter. We report ...first preliminary results on invariant masses e+e--pairs which were measured in 12C + 12C collisions at Ekin=2 GeVdot operatorA. The analysis methods are briefly outlined and a comparison with detailed Monte-Carlo simulations is shown.
The aim of the present analysis is to determine the relative production cross sections of the Λ(1405) and Σ(1385)0 resonances in p+p collisions at Ekin = 3.5 GeV measured with HADES. Upper and lower ...limits have been determined for the ratio \documentclass12pt{minimal}
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\begin{document}$\sigma_{(\Sigma(1385)^{0}+p+K^{+})}/\sigma_{(\Lambda(1405)+p+K^{+})}=0.76_{-0.26}^{+0.54}$\end{document}. The knowledge of this ratio is an essential input for the analysis of the decay Λ(1405)→Σ±π ∓ , where an unambiguous separation of the Λ(1405) and Σ(1385)0 signals is not possible.
e+e− production was studied using the High Acceptance DiElectron Spectrometer (HADES). In pp collisions at 2.2 GeV kinetic beam energy, the exclusive η production and the Dalitz decay η → γe+e− have ...been reconstructed. The electromagnetic form factor of the latter decay was found to be in good agreement with the existing theoretical predictions. In addition, an inclusive e+e− invariant-mass spectrum from the 12C + 12C reaction at 2 AGeV is presented and compared with a simplified thermal model.
