ISSN - 0217751X, International Journal of Modern Physics A, 2011, vol. 26, p. 702-704
The pp → ppπ0π0 reaction and its limiting case, fusion to quasi-bound 2He, in search of the ABC effect
The π0π0 production in pp-collisions has been investigated in exclusive and kinematically complete measurements from threshold up to Tp = 1.4 GeV. For incident energies Tp > 1 GeV, i.e. in the region beyond the Roper excitation, the ΔΔ excitation process takes over. The data are well explained by the t-channel ΔΔ process dominated by pion exchange. There is no low-mass enhancement (ABC effect) in the π0π0-invariant mass distribution beyond that given by the conventional t-channel ΔΔ process. This is also true for the limiting case, where the protons are in the quasi-bound 2He state. © 2011 World Scientific Publishing Company.