Observation of Δ+→ pπ0 decay in heavy-ion collisions
Abstract
Proton-π0 coincidences have been measured at the beam energy of 180A MeV in the reaction Ar+Ca studied by TAPS at SIS/GSI. In the proton-π0 invariant mass spectrum we observe a significant excess of strength above the background obtained by event mixing. We attribute this signal to the strength distribution NΔ of the Δ baryonic resonance. No correlation is observed in the case of deuteron-π0 coincidences. Assuming isotropic emission of π0 and Δ+ from a midrapidity thermal source and isospin symmetry, we determined the global NΔ/Nπratio of 0.79 ±0.30(stat) ±0.2(syst). This value indicates that most pions produced at subthreshold energy in heavy-ion reaction are mediated by the Δ-resonance.
- Publication:
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European Physical Journal A
- Pub Date:
- October 2000
- DOI:
- 10.1007/s100500070057
- Bibcode:
- 2000EPJA....9...69M
- Keywords:
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- PACS. 25.70.-z Low and intermediate energy heavy-ion reactions –
- 25.75.Dw Particle and resonance production –
- 14.20.Gk Baryon resonances with S = 0;
- PACS. 25.70.-z Low and intermediate energy heavy-ion reactions – 25.75.Dw Particle and resonance production – 14.20.Gk Baryon resonances with S = 0