ISSN - 0217751X, International Journal of Modern Physics A, 2007, vol. 22, p. 509-513

ππ Production in proton-proton collisions

Skorodko T., Bashkanov M., Bogoslowsky D., Calén H., Cappellaro F., Clement H., Demiroers L., Ekström C., Fransson K., Greiff J., Gustafsson L., Höistad B., Ivanov G., Jacewicz M., Jiganov E., Johansson T., Kaskulov M. M., Keleta S., Khakimova O., Koch I., Kren F., Kullander S., Kupść A., Kuznetsov A., Marciniewski P., Meier R., Morosov B., Oelert W., Pauly C., Petukhov Y., Povtorejko A., Ruber R. J M Y, Schwick A., Scobel W., Shafigullin R., Shwartz B., Sopov V., Stepaniak J., Tchernyshev V., Thörngren-Engblom P., Tikhomirov V., Turowiecki A., Wagner G. J., Wolke M., Yamamoto A., Zabierowski J., Złomanćzuk J.

At CELSIUS-WASA the two-pion production in proton-proton collisisons has been measured exclusively from threshold up to the energy regime, where both of the collision partners are expected to be excited to the Δ state. The measurements constitute the first kinematically complete data samples of solid statistics in this energy range. Most of the data have been obtained for the π+π- and π0π0 channels. Whereas at near-threshold energies the differential distributions can be succesfully explained by chiral dynamics and Roper excitation, respectively, the data for the π+π- channel in the ΔΔ region can be described only, if the special configuration (ΔΔ) 0+ is assumed. The data for the π0π0 channel moreover exhibit a low-mass enhancement in the π0π 0 invariant mass spectrum, which is reminiscent of the ABC-effect found in double-pionic fusion to light nuclei. © World Scientific Publishing Company.