[en] Short communication

[en] Experimental results (mostly from the DLS collaboration at LBL) and model calculations of dielectron production in pp/pd/pBe (1-5 GeV) and CaCa (1-2 GeV/A) are presented. Dileptons appear to be a suitable probe to approach in-medium properties of hadrons in nuclear matter. At the present time, the ρ/ω region looks the most promising. Oncoming programs are briefly presented, in particular the HADES project at GSI. 7 figs

[en] We discuss the DLS p-Be data at 1.0, 2.1 and 4.9 GeV, and model calculations that illustrate the various possible mechanisms of dilepton production at intermediate energy. It appears that the origin of dileptons is not presently understood, which is further supported by the recent DLS p-p and p-d preliminary results at 4.9 GeV. More thoughts and both theoretical and experimental works are needed

[en] We discuss the physics objectives of the DLS program with some emphasis on the possible use of dileptons as a probe of pion dynamics in nuclear matter. Data on p + Be reactions at 1-5 GeV and Ca + Ca at 1 GeV/A are presented. The observation of a structure at twice the pion mass in the e⁺e/sup /minus// invariant mass spectra above 2 GeV beam energy and the excitation function for the p + Be reaction suggest that pion annihilation is the main dielectron source above 2 GeV. The dielectron mass spectrum from Ca + Ca at 1 GeV/A exhibits an inverse slope larger than the one from p + Be at the same beam energy. 14 refs., 9 figs., 1 tab

[en] Published in summary form only. 4 figs

[en] A brief review of the direct production of single leptons and dileptons in hadronic collisions at low p/sub t/ and low pair mass is given. Several open questions are pointed out and the universality of lepton production is briefly discussed. The Bevalac Di-Lepton Spectrometer project is presented. 25 refs., 5 figs

[en] We discuss the physics objectives for the DLS program with some emphasis on the possible use of dileptons as a probe of pion dynamics in nuclear matter. Data on p-Be reactions at 1-5 GeV and Ca-Ca at 1-2 A GeV are presented. The observation of a structure at about twice the pion mass in the e⁺e^- invariant mass spectra above 2 GeV beam energy and the excitation function for the p-Be reaction suggest that pion annihilation is a significant dielectron source above 2 GeV. The dielectron mass spectrum from Ca-Ca at 1 A GeV exhibits an inverse slope larger than the one from p-Be at the same beam energy. 22 refs., 12 figs., 3 tabs

No abstract available

[en] A brief review of the direct production of single leptons and dileptons in hadronic collisions at low pt and low pair mass is given. Several open questions are pointed out and the universality of lepton production is briefly discussed. The Bevalac Di-Lepton Spectrometer project is presented

[en] We report on preliminary results of direct electron pair measurements in p+Be at 4.9 GeV and 2.1 GeV and Ca+Ca at 1.95 GeVA collisions at the Bevalac. The results are compared to existing data in p+Be at 12.1 GeV and π^-p at 15.9 and 16.9 GeV