학술논문
Delta Delta Excitation in Proton-Proton Induced pi0pi0 Production
Document Type
Working Paper
Author
Skorodko, T.; Bashkanov, M.; Bogoslawsky, D.; Calen, H.; Clement, H.; Doroshkevich, E.; Demiroers, L.; Ekstroem, C.; Fransson, K.; Gustafsson, L.; Hoistad, B.; Ivanov, G.; Jacewicz, M.; Jiganov, E.; Johansson, T.; Khakimova, O.; Keleta, S.; Koch, I.; Kren, F.; Kullander, S.; Kupsc, A.; Marciniewski, P.; Meier, R.; Morosov, B.; Pauly, C.; Petren, H.; Petukhov, Y.; Povtorejko, A.; Ruber, R. J. M. Y.; Schoenning, K.; Scobel, W.; Shwartz, B.; Stepaniak, J.; Thoerngren-Engblom, P.; Tikhomirov, V.; Wagner, G. J.; Wolke, M.; Yamamoto, A.; Zabierowski, J.; Zlomanczuk, J.
Source
Phys.Lett.B695:115-123,2011
Subject
Language
Abstract
Exclusive measurements of the $pp \to pp\pi^0\pi^0$ reaction have been performed at CELSIUS/WASA at energies from threshold up to $T_p$ = 1.3 GeV. Total and differential cross sections have been obtained. Here we concentrate on energies $T_p \ge$ 1 GeV, where the $\Delta\Delta$ excitation becomes the leading process. No evidence is found for a significant ABC effect beyond that given by the conventional $t$-channel $\Delta\Delta$ excitation. This holds also for the double-pionic fusion to the quasibound $^2$He. The data are compared to model predictions, which are based on both pion and $\rho$ exchange. Total and differential cross sections are at variance with these predictions and call for a profound modification of the $\rho$-exchange. A phenomenological modification allowing only a small $\rho$ exchange contribution leads to a quantitative description of the data.