Browsing by Author "HADES collaboration (105 authors)"
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- Highlights of Resonance Measurements With HADESPublication . HADES collaboration (105 authors); Blanco, A.; Bordalo, P.; Fonte, P.; Franco, C.; Lopes, L.; Mangiarotti, A.; Silva, L.This contribution aims to give a basic overview of the latest results regarding the production of resonances in different collision systems. The results were extracted from experimental data collected with HADES that is a multipurpose detector located at the GSI Helmholtzzentrum, Darmstadt. The main points discussed here are: the properties of the strange resonances Lambda(1405) and Sigma(1385), the role of Delta's as a source of pions in the final state, the production dynamics reflected in form of differential cross sections, and the role of the phi meson as a source for K^- particles.
- Investigating hadronic resonances in pp interactions with HADESPublication . HADES collaboration (105 authors); Blanco, A.; Bordalo, P.; Fonte, P.; Franco, C.; Lopes, L.; Mangiarotti, A.; Silva, L.In this paper we report on the investigation of baryonic resonance production in proton-proton collisions at the kinetic energies of 1.25 GeV and 3.5 GeV, based on data measured with HADES. Exclusive channels nppi^+ and pppi^0 as well as ppe^+e^- were studied simultaneously in the framework of a one-boson exchange model. The resonance cross sections were determined from the one-pion channels for Delta(1232) and N(1440) (1.25 GeV) as well as further Delta and N* resonances up to 2 GeV/c^2 for the 3.5 GeV data. The data at 1.25 GeV energy were also analysed within the framework of the partial wave analysis together with the set of several other measurements at lower energies. The obtained solutions provided the evolution of resonance production with the beam energy, showing a sizeable non-resonant contribution but with still dominating contribution of Delta(1232)P_33. In the case of 3.5 GeV data, the study of the ppe^+e^- channel gave the insight on the Dalitz decays of the baryon resonances and, in particular, on the electromagnetic transition form-factors in the time-like region. We show that the assumption of a constant electromagnetic transition form-factors leads to underestimation of the yield in the dielectron invariant mass spectrum below the vector mesons pole. On the other hand, a comparison with various transport models shows the important role of intermediate rho production, though with a large model dependency. The exclusive channels analysis done by the HADES collaboration provides new stringent restrictions on the parameterizations used in the models.
- Measurement of the quasi free $np \to np\pi^+\pi^-$ and $np \to pp\pi^-\pi^0$ reactions at 1.25 GeV With HADESPublication . HADES collaboration (105 authors); Blanco, A.; Bordalo, P.; Fonte, P.; Franco, C.; Lopes, L.; Mangiarotti, A.; Silva, L.We present the results of two-pion production in tagged quasi-free np collisions at a deutron incident beam energy of 1.25 GeV/c measured with the High-Acceptance Di-Electron Spectrometer (HADES) installed at GSI. The specific acceptance of HADES allowed for the first time to obtain high-precision data on pi^+pi^- and pi^-pi^0 production in np collisions in a region corresponding to large transverse momenta of the secondary particles. The obtained differential cross section data provide strong constraints on the production mechanisms and on the various baryon resonance contributions (DeltaDelta, N(1440), N(1520), Delta(1600)). The invariant mass and angular distributions from the np -> nppi^+pi ^-and np -> pppi^-pi^0 reactions are compared with different theoretical model predictions.
- Strange hadron production at SIS energies: an update from HADESPublication . HADES collaboration (105 authors); Blanco, A.; Bordalo, P.; Fonte, P.; Franco, C.; Lopes, L.; Mangiarotti, A.; Silva, L.We present and discuss recent experimental activities of the HADES collaboration on open and hidden strangeness production close or below the elementary NN threshold. Special emphasis is put on the feed-down from ϕ mesons to antikaons, the presence of the Ξ(-) excess in cold nuclear matter and the comparison of statistical model rates to elementary p+p data. The implications for the interpretation of heavy-ion data are discussed as well.