Inclusive meson production in 3.5 GeV pp collisions studied with the HADES spectrometer

We present the inclusive di‐electron invariant‐mass spectrum from p+p interactions at 3.5 GeV kinetic beam energy. It is a very important reference for the study of vector meson production off the nucleus, recently investigated by HADES in p+93Nb reactions at the same beam energy. Up to invariant masses of 0.6 GeV/c2 the main contributions to the e+e− spectrum are π0, η, ω and Δ Dalitz decays. In the vector‐meson region a clear peak corresponding to the ω direct decay is reconstructed with ≈2% mass resolution. Subtracting this peak from the spectrum allows to investigate additional sources, in particular the ρ meson. Indeed, the latest results from HSD and UrQMD calculations show different distributions for the shape of the ρ meson at these energies. Therefore it is important to experimentally understand the production mechanism of the ρ meson in elementary reactions. Besides the spectral shape of the mesons, their inclusive production cross sections are also not known at these energies. Due to the large ...