Open Access

Witold Przygoda, Jörn Adamczewski-Musch, Oliver Werner Arnold, Ermias T. Atomssa, Claudia Behnke, Jia-Chii Berger-Chen, Jacek Biernat, Alberto Blanco, Christoph Blume, Michael Böhmer, Paula Bordalo, Sergey P. Chernenko, Christina Anna Deveaux, Adrian Dybczak, Eliane Epple, Laura Fabbietti, Oleg Fateev, Paulo Fonte, Celso Franco, Jürgen Friese, Ingo Fröhlich, Tetyana Galatyuk, Juan A. Garzón, Katharina Gill, Marina Golubeva, Fedor Guber, Malgorzata Gumberidze, Szymon Harabasz, Thierry Hennino, Stanislav Hlaváč, Claudia Höhne, Romain Holzmann, Alexander P. Ierusalimov, Alexander Ivashkin, Martin Jurkovič, Burkhard Kämpfer, Tatiana L. Karavicheva, Behruz Kardan, Ilse Koenig, Wolfgang Koenig, Burkhard W. Kolb, Grzegorz Korcyl, Georgy Kornakov, Roland Kotte, Antonin Krása, Erik Krebs, Hubert Kuc, Andrej Kugler, Tobias Kunz, Alexander Kurepin, Aleksey K. Kurilkin, Pavel Kurilkin, Vladimir P. Ladygin, Rafał Tomasz Lalik, Kirill Lapidus, Alexei Lebedev, Luis Alberto Vieira Lopes, Manuel Lorenz, Tariq Mahmoud, Ludwig W. Maier, Alessio Mangiarotti, Jochen Markert, Volker Metag, Jan Michel, Christian Müntz, Robert Helmut Münzer, Lothar Naumann, Marek Palka, Yannis Parpottas, Vladimir Pechenov, Olga Pechenova, Vlasios Petousis, Jerzy Pietraszko, Béatrice Ramstein, Laura Rehnisch, Andrey Reshetin, Adrian Rost, Anar Rustamov, Alexander Sadovsky, Piotr Salabura, Timo Scheib, Korbinian Schmidt-Sommerfeld, Heidi Schuldes, Patrick Sellheim, Johannes Stephan Siebenson, Luis Silva, Yuri G. Sobolev, Stefano Spataro, Herbert Ströbele, Joachim Stroth, Paweł Strzempek, Christian Thomas Sturm, Ondřej Svoboda, Attilio Tarantola Peloni, Khaled Teilab, Pavel Tlustý, Michael Traxler, Haralabos Tsertos, Taras A. Vasiliev, Vladimir Wagner, Christian Wendisch, Joana Wirth, Jörn Wüstenfeld, Yuri V. Zanevsky, Peter W. Zumbruch

• n 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 npπ+ and ppπ0 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 Δ(1232) and N(1440) (1.25 GeV) as well as further Δ and N* resonances up to 2 GeV/c2 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 Δ(1232)P33. 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 ρ 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.