Seminarium fizyki jądra atomowego
Dnia 13 listopada 2014 odbyło się seminarium pt.
„Production and Dalitz decays of baryon resonances in p+p interactions at 1.25 and 3.5 GeV beam energy with HADES”
prelegent: dr Witold Przygoda (Instytut Fizyki, Uniwersytet Jagielloński)
Streszczenie: HADES is a versatile magnetic spectrometer installed at GSI Darmstadt at SIS18. Thanks to its high acceptance, powerful particle identification and very good mass resolution it allows to study both hadron and dilepton production in πp, πA, pp, pA and AA collisions at a few AGeV beam energy range. In pp collisions at 1.25 GeV, the intermediate Δ(1232) resonance is expected to play a dominant role in the pion production. The resonance cross section was determined from exclusive ppπo and pnπ+ channels in the framework of a OPE model. In e+e- production, two major sources, πo and Δ(1232), are expected to play dominant role. In particular, for the first time Δ(1232) has been reconstructed exclusively via the pe+e- decay channel and the branching ratio of electromagnetic Dalitz decay has been extracted. At higher kinetic energy (3.5 GeV) dielectron pair production is determined by Dalitz decays of neutral mesons and baryonic resonances and, in the high mass region, by two body decays of ω and ρ. At this beam energy the dilepton invariant mass distribution appears to be sensitive to the structure of the baryon resonance electromagnetic transition form-factors in the time like-region. In the presentation the data are compared to various theoretical predictions.