Dielectron production in C-12_s16C-12 collisions at 2-AGeV with HADES
Keywords
scattering: heavy ion, carbon, electron: pair production, mass spectrum: (positron electron), model: production, pseudoscalar meson: decay, vector meson: decay, spectral representation, quantum molecular dynamics: relativistic, magnetic spectrometer: experimental results, Darmstadt SIS | 1-2 GeV/nucleon
Abstract
The invariant-mass spectrum of $e^_s16 e^-$ pairs produced in $^{12}$C_s16$^{12}$C collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over five orders of magnitude from the $pi^0$-Dalitz to the $rho/omega$ invariant-mass region. Dalitz decays of $pi^0$ and $eta$ account for all the yield up to 0.15 GeV/c$^2$, 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.
