Dielectron production in C12+C12 collisions at 2AGeV with the HADES spectrometer

The invariant-mass spectrum of e+e- pairs produced in C12+C12 collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over 5 orders of magnitude from the π0-Dalitz to the ρ/ω invariant-mass region. Dalitz decays of π0 and η account for all the yield up to 0.15GeV/c2, but for only about 50% above this mass. A comparison with model calculations shows that the excess pair yield is likely due to baryon-resonance and vector-meson decays. Transport calculations based on vacuum spectral functions fail, however, to describe the entire mass region. © 2007 The American Physical Society. 98 5 Cited By :118