Two-pion production in the Delta Delta region: Is the ABC-effect the result of a resonance in the pn Delta Delta system?

CELSIUS-WASA Collaboration, M. Bashkanov*, H. Clement, O. Khakimova, F. Kren, A. Pricking, T. Skorodko, G. J. Wagner

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The ABC effect - a puzzling low-mass enhancement in the pi pi invariant mass spectrum - is known from inclusive measurements of two-pion production in nuclear fusion reactions. Exclusive measurements conducted at CELSIUS-WASA for the fusion reactions leading to d and He-3 in the final state reveal the ABC effect to be of scalar-isoscalar nature and to be associated with the formation of a resonance in the pn Delta Delta systems in the intermediate state. The differential distributions for the pi(0)pi(0) channels can be well described, if a quasi-bound state within the AA system is assumed, which gives rise to a resonance structure in the total cross section. This ansatz is capable of describing all differential cross sections including the results of previous inclusive measurements on He-4 as well as the energy dependence of the total cross sections.

Original languageEnglish
Title of host publicationMESON PHYSICS AT COSY - 11 AND WASA-AT- COSY
EditorsA Kupsc, P Moskal, M Wolke
PublisherAMER INST PHYSICS
Pages256-258
Number of pages3
ISBN (Print)978-0-7354-0464-9
Publication statusPublished - 1 Jan 2007
EventInternational Symposium on Meson Physics at COSY-11 and WASA-AT-COSY - Cracow, Poland
Duration: 17 Jun 200722 Jun 2007

Publication series

NameAIP CONFERENCE PROCEEDINGS
PublisherAMER INST PHYSICS
Volume950
ISSN (Print)0094-243X

Conference

ConferenceInternational Symposium on Meson Physics at COSY-11 and WASA-AT-COSY
Country/TerritoryPoland
CityCracow
Period17/06/0722/06/07

Keywords

  • ABC effect
  • Delta Delta resonance
  • GEV-C
  • MODEL

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