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- Khakimova, O., et al.
(author)
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Observation of the abc effect in the first exclusive measurements of pn -> d pi(0)pi(0)
- 2007
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In: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 22:2-3, s. 617-620
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Journal article (peer-reviewed)abstract
- The reaction pn → dπ0π0 constitutes the most fundamental system for the study of the ABC effect - a puzzling threshold enhancement in the ππ invariant mass spectrum of the ππ system in double-pionic fusion to nuclear bound states. The first exclusive measurements of this reaction have now been carried out at CELSIUS-WASA. They exhibit a striking low-mass enhancement in the ππ invariant mass spectrum, prove it to be a σ-channel phenomenon and falsify conventional theoretical models, which predict an associated high-mass enhancement not present in the new exclusive data. In the kinematically complete data sample we observe a ΔΔ excitation, where the interaction between the two Δ obviously plays a crucial role for the generation of the ππ low-mass enhancement.
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