Eur. Phys. J. A 14, 113-124 (2002)
Role of exchange for annihilation into two-pion and three-pion channelsM. Betz1, E.A. Veit1 and J. Haidenbauer2
1 Instituto de Física - Universidade Federal do Rio Grande do Sul, Cx. P. 15051; CEP 91501-970, Porto Alegre, Brazil
2 Institut für Kernphysik, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
(Received: 16 January 2002 Communicated by V.V. Anisovich)
annihilation into two pions and three pions is studied in a baryon exchange model. Annihilation diagrams involving nucleon as well as -resonance exchanges are included consistently in the two- and three-pion channels. Effects from the initial-state interaction are fully taken into account. A comparison of the influence of the exchange on the considered annihilation channels is made and reveals that its importance for three-pion annihilation is strongly reduced as compared to two-pion annihilation. It is found that annihilation into three uncorrelated pions can yield up to 10% of the total experimentally observed three-pion annihilation cross-section.
13.75.Cs - Nucleon-nucleon interactions (including antinucleons, deuterons, etc.).
14.20.-c - Baryons (including antiparticles).
21.30.Cb - Nuclear forces in vacuum.
25.43.+t - Antiproton-induced reactions.
© Società Italiana di Fisica, Springer-Verlag 2002