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- Bashkanov, M., et al.
(author)
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Low-mass pi pi enhancement in baryonic pi pi production : ABC effect revised by exclusive measurements
- 2007
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In: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 22:2-3, s. 625-628
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Journal article (peer-reviewed)abstract
- The ABC effect - a puzzling threshold enhancement in the ππ invariant mass spectrum of double-pionic fusion to nuclear bound states - has been investigated since 40 years by inclusive measurements without providing a conclusive interpretation. First exclusive measurements to this topic have now been carried out at CELSIUS-WASA. They confirm a huge ππ threshold enhancement, prove it to be of scalar-isoscalar nature, i.e., a σ-channel phenomenon and reveal the theoretically predicted high-mass enhancement in inclusive spectra to be of πππ rather than of ππ nature - falsifying thus corresponding model predictions for the ABC effect. From the kinematically complete data samples we infer that the interaction between the two Δ particles created in this process is of crucial importance.
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