763 articles – 7611 Notices  [english version]
 HAL : in2p3-00714011, version 1
 Inclusive dielectron spectra in p plus p collisions at 3.5 GeV kinetic beam energyAgakishiev G., L. Boyard J., Gumberidze M., Hennino T., Morinière E. et alEuropean Physical Journal A: Hadrons and Nuclei 48 (2012) 64 - http://hal.in2p3.fr/in2p3-00714011
Physique/Physique Nucléaire Expérimentale
Inclusive dielectron spectra in p plus p collisions at 3.5 GeV kinetic beam energy
G. Agakishiev, J. L. Boyard1, M. Gumberidze1, T. Hennino1, E. Morinière1, B. Ramstein1
 1 : IPNO - Institut de Physique Nucléaire d'Orsay http://ipnweb.in2p3.fr CNRS : UMR8608 – IN2P3 – Université Paris XI - Paris Sud IPN - 15, rue Georges Clemenceau - 91406 ORSAY CEDEX France
We present the inclusive invariant mass, transverse momentum and rapidity distributions of dielectrons (e+e- pairs) in p+p interactions at 3.5GeV beam kinetic energy. In the vector meson mass region, a distinct peak corresponding to direct ω decays is reconstructed with a 2% mass resolution. The data is compared to predictions from three model calculations. Due to the large acceptance of the HADES apparatus for e+e- invariant masses above 0.2 GeV/c 2 and for transverse pair momenta p t < 1 GeV/c, acceptance corrections are, to a large extent, model independent. This allows us to extract from dielectron data for the first time at this energy the inclusive production cross-sections for light vector mesons. Inclusive production cross-sections for π0 and η mesons are also reported. The obtained results will serve as an important reference for the study of vector meson production in proton-nucleus and heavy-ion collisions. Furthermore, using this data, an improved value for the upper bound of the branching ratio for direct η decays into the electron-positron channel is obtained.