Exclusive Measurement of the $pp \to nnπ^+π^+$ Reaction at 1.1 GeV
nucl-ex
/ Authors
M. Bashkanov, D. Bogoslawsky, H. Calen, H. Clement, E. Doroshkevich, L. Demiroers, C. Ekstrom, K. Fransson, L. Gustafsson, B. Hoistad
and 29 more authors
G. Ivanov, M. Jacewicz, E. Jiganov, T. Johansson, O. Khakimova, S. Keleta, I. Koch, F. Kren, S. Kullander, A. Kupsc, P. Marciniewski, R. Meier, B. Morosov, C. Pauly, H. Petren, Y. Petukhov, A. Povtorejko, R. J. M. Y. Ruber, K. Schonning, W. Scobel, B. Shwartz, J. Stepaniak, P. Thorngren-Engblom, V. Tikhomirov
/ Abstract
First exclusive data for the $pp \to nnπ^+π^+$ reaction have been obtained at CELSIUS with the WASA detector setup at a beam energy of $T_p$ = 1.1 GeV. Total and differential cross sections disagree with theoretical calculations, which predict the $ΔΔ$ excitation to be the dominant process at this beam energy. Instead the data require the excitation of a higher-lying $Δ$ state, most likely the $Δ(1600)$, to be the leading process.