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HK: Fachverband Physik der Hadronen und Kerne
HK 34: Postersitzung
HK 34.6: Poster
Thursday, March 13, 2008, 14:00–16:00, Poster C3
Measurement of the pp → dπ+π0 Reaction - ΔΔ Excitation without ABC-Effect * — •Florian Kren, Mikhail Bashkanov, Heinz Clement, Evgueny Doroshkevich, Olena Khakimova, Tatiana Skorodko, and Gerhard J. Wagner for the CELSIUS-WASA collaboration — Physikalisches Institut der Universität Tübingen
Inclusive measurements of double-pionic fusion indicate that isovector ππ channels should not exhibit any ABC effect, which is a low-mass enhancement in the invariant ππ mass spectrum.
At CELSIUS-WASA we conducted the first exclusive experiments on this issue by measuring the reaction pp → dπ+π0. In this talk first results will be presented for the measurements at Tp = 1.1 GeV, i.e. in the energy region, where the ABC-effect is supposed to be largest and the ΔΔ excitation already should be the dominant process.
The dπ+π0 data reveal that indeed the ABC-effcet is absent in this reaction despite a strong ΔΔ excitation, which is clearly seen in the dπ invariant mass spectra. The distribution of the π+π0 opening angle is consistent with a spinflip p-wave distribution. The results will be compared to those from the isoscalar double-pion production in the fusion reaction pn → dπ0π0, where a huge ABC-effect is observed.
The total cross section of this reaction also does not exhibit the peculiar resonance-like behavior of the dπ0π0 channel. It rather agrees with simple ΔΔ calculations without mutual interaction between the Δ states.
*supported by BMBF, COSY-FFE and DFG(Eur. Graduate School)