Baryonic resonances close to the (K)over-barN threshold: The case of Lambda (1405) in pp collisions

Agakishiev, G.; Balanda, A.; Belver, D.; Belyaev, A.; Berger Chen, J.; Blanco, A.; Böhmer, M.; Boyard, J.; Cabanelas, P.; Castro, E.; Chernenko, S.; Christ, T.; Destefanis, MARCO GIOVANNI; Dohrmann, F.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Finocchiaro, P.; Fonte, P.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J.; Gernhäuser, R.; Gilardi, C.; Golubeva, M.; González Díaz, D.; Guber, F.; Gumberidze, M.; Heinz, T.; Hennino, T.; Holzmann, R.; Ierusalimov, A.; Iori, I.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Kanaki, K.; Karavicheva, T.; Koenig, I.; Koenig, W.; Kolb, B.; Kotte, R.; Krása, A.; Krizek, F.; Krücken, R.; Kuc, H.; Kühn, W.; Kugler, A.; Kurepin, A.; Lalik, R.; Lang, S.; Lange, J.; Lapidus, K.; Liu, T.; Lopes, L.; Lorenz, M.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michalska, B.; Michel, J.; Morinière, E.; Mousa, J.; Müntz, C.; Münzer, R.; Naumann, L.; Otwinowski, J.; Pachmayer, Y.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Reshetin, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Schmah, A.; Schwab, E.; Siebenson, J.; Sobolev, Y. u.; Spataro, STEFANO GIOVANNI; Spruck, B.; Ströbele, H.; Stroth, J.; Sturm, C.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Trebacz, R.; Tsertos, H.; Wagner, V.; Weber, M.; Wendisch, C.; Wüstenfeld, J.; Yurevich, S.; Zanevsky, Y.

doi:10.1103/PhysRevC.87.025201

We present an analysis of the Lambda(1405) resonance produced in the reaction p + p -> Sigma(+/-) + pi(-/+) + K+ + p at 3.5 GeV kinetic beam energy measured with the High Acceptance Dielectron Spectrometer (HADES) at the Gesellschaft fur Schwerionenforschung (GSI). The two charged decay channels Lambda (1405) -> Sigma(+/-) + pi(-/+) have been reconstructed for the first time in p + p collisions. The efficiency and acceptance- corrected spectral shapes show a peak position clearly below 1400MeV/c(2). We find a total production cross section of sigma(Lambda(1405)) = (1405) = 9.2 +/- 0.9 +/- 0.7(-1.0)(+3.3)mu b . The analysis of its polar angle distribution suggests that the Lambda(1405) is produced isotropically in the p - p center-of-mass system (CMS).