Investigation of near-threshold eta-meson production in the reaction π - p→ ηn
Abstract
Differential and total cross sections for eta-meson production in the reaction π - p → ηn were measured within the experimental program eta-meson physics implemented in the pion channel of the synchrocyclotron of the Petersburg Nuclear Physics Institute (PNPI, Gatchina). These measurements were performed at incident-pion momenta (700, 710, 720, and 730 MeV/ c) in the vicinity of the threshold for the process under study by using the neutral-meson spectrometer designed and created at the Meson Physics Laboratory of PNPI. It is shown that, in the immediate vicinity of the threshold (685 MeV/ c), the process of eta-meson production proceeds predominantly via S 11(1535)-resonance formation followed by the decay S 11(1535) → ηn (the respective branching fraction is Br ≈ 60%), but that, as the momentum of incident pions increases, the role of the D wave becomes ever more important. A detailed analysis of this effect indicates that it is due to the increasing contribution of the D 13(1520) resonance. Although the branching fraction of the decay of this resonance through the ηn channel is assumed to be very small (BR ≈ 0.24%), the effect is enhanced owing to the interference between the D wave and the dominant resonance S 11(1535).
- Publication:
-
Physics of Atomic Nuclei
- Pub Date:
- August 2012
- DOI:
- 10.1134/S1063778812080042
- Bibcode:
- 2012PAN....75..923B