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Dielectron production in 12C+12C collisions at 2A GeV with the HADES spectrometer |
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| Authors: | Agakichiev G Agodi C Alvarez-Pol H Bałanda A Bertini D Bielcik J Bellia G Böhmer M Bokemeyer H Boyard J L Braun-Munzinger P Cabanelas P Chernenko S Christ T Coniglione R Cosentino L Díaz J Dohrmann F Durán I Eberl T Enghardt W Fabbietti L Fateev O Fernandez C Finocchiaro P Friese J Fröhlich I Fuentes B Garabatos C Garzón J A Gernhäuser R Gilardi C Golubeva M González-Díaz D Grosse E Guber F Hennino T Hlavac S Holzmann R Homolka J Ierusalimov A Iori I Ivashkin A Jaskuła M Jurkovic M Kagarlis M Kajetanowicz M Kämpfer B Kanaki K Karavicheva T Kastenmüller A Kidoń L Kienle P Koenig I Koenig W |
| Institution: | II.Physikalisches Institut, Justus Liebig Universit?t Giessen, 35392 Giessen, Germany. |
| Abstract: | The invariant-mass spectrum of e+e- pairs produced in 12C+12C 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 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. |
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