Abstract
Nucleon-antinucleon at rest presents a variety of channels, where wide mesons often interfere, as shown by the analysis of protonium decay into three pions by the Asterix and Crystal Barrel experiments. A statistical model for emission of the narrow mesonsπ, η, η′ ω, K, ¯K is presented to account for the general profile of the reaction. It is an alternative to a model based on two-doorway state dominance proposed earlier. It allows direct prediction with phenomenological channels, but deals only with branching ratios, not with the detailed structure of the final states. The initial state interactions do not influence the bulk of predictions, although they matter for two-particle branching ratios, which are small. The model is in reasonable agreement with present experimental data and is offered as a standard for comparison with forthcoming results. Some obvious deviations claim for a dynamical explanation.
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It it a pleasure to thank C. Amsler and L. Montanet for friendly and informative discussions. The invaluable help of M.-P. Biémont-Gérard in the preparation of the manuscript is gratefully acknowledged.