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Dielectron production in Ar + KCl collisions at 1.76A GeV

Abstract : We present results on dielectron production in 40Ar+KCl collisions at 1.76A GeV. For the first time ω mesons could be reconstructed in a heavy-ion reaction at a bombarding energy which is well below the production threshold in free nucleon-nucleon collisions. The ω multiplicity has been extracted and compared to the yields of other particles, in particular of the φ meson. At intermediate e+e− invariant masses, we find a strong enhancement of the pair yield over a reference spectrum from elementary nucleon-nucleon reactions, suggesting the onset of nontrivial effects of the nuclear medium. Transverse-mass spectra and angular distributions have been reconstructed in three invariant mass bins. In the former unexpectedly large slopes are found for high-mass pairs. The latter, in particular the helicity-angle distributions, are largely consistent with expectations for a pair cocktail dominated at intermediate masses by Δ Dalitz decays.
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Contributor : Sophie Heurteau <>
Submitted on : Tuesday, August 23, 2011 - 4:46:58 PM
Last modification on : Wednesday, September 16, 2020 - 4:10:32 PM

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G. Agakishiev, A. Balanda, B. Bannier, R. Bassini, D. Belver, et al.. Dielectron production in Ar + KCl collisions at 1.76A GeV. Physical Review C, American Physical Society, 2011, 84, pp.014902. ⟨10.1103/PhysRevC.84.014902⟩. ⟨in2p3-00616668⟩



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