Inclusive dielectron spectra in p+ p collisions at 3.5 GeV kinetic beam energy

HADES collaboration, G Agakishiev, A Balanda… - The European Physical …, 2012 - Springer
HADES collaboration, G Agakishiev, A Balanda, D Belver, A Belyaev, A Blanco, M Boehmer…
The European Physical Journal A, 2012Springer
We present the inclusive invariant mass, transverse momentum and rapidity distributions of
dielectrons (e+ e-pairs) in p+ p interactions at 3.5 GeV 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 pt< 1 GeV/c, acceptance corrections are, to a large …
Abstract
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/c2 and for transverse pair momenta pt < 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.
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