The four-prong annihilation of 1.2 GeV/ c antiprotons in hydrogen (I): Four-pion final state

• Published in: Nuclear physics. B Vol. 6; no. 2; pp. 174 - 186
• Main Authors: Donald, R.A., Edwards, D.N., Moore, R.S., Read, E.J.C., Reucroft, S., Frodesen, A.G., Jacobsen, T., Sire, S., Skjeggestad, O., Saetre, P., Tøfte, H., Bettini, A., Limentani, S., Peruzzo, L., Santangelo, R., Sartori, S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1968
• ISSN: 0550-3213; 1873-1562
• DOI: 10.1016/0550-3213(68)90278-2

Approximately 17 000 four-prong annihilations of 1.2 GeV/ c antiprotons in hydrogen have been analyzed. The cross section for annihilation into four prongs is 31.6 ± 1.0 mb and the partial cross section for the 4 π final state 2.9 ± 0.2 mb. The 4 π state, which is reported here, shows production of ϱ 0, f 0, A 2 ± mesons and an enhancement in the 3 π and/or ϱπ system at the mass of the A 1 meson. The frequencies of various resonance channels have been determined. Two-body intermediate states account for 40–60% of the 4 π final state. Centre-of-mass angular distributions of the pions are presented. A change in the momentum dependence of the forward-backward asymmetry of the pions is observed at a pion momentum corresponding to the production of A 2 ± π +.