Gießen 2007 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 45: Elektromagnetische und Hadronische Sonden
HK 45.1: Talk
Thursday, March 15, 2007, 14:15–14:30, A
σ-Channel Threshold Enhancement in Double-Pionic Fusion* — •Mikhail Bashkanov, Heinz Clement, Olena Khakimova, Florian Kren, Annette Pricking, Tatiana Skorodko, and Gerhard Wagner for the CELSIUS-WASA collaboration — Physikalisches Institut der Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen
The double-pionic fusion process has been measured at CELSIUS-WASA for the first time exclusively and kinematically completely for the basic reaction pn→ dπ0π0 at Tp=1.04 GeV as well as for dp→ 3He π0π0 and 3He π+π− at Tp=0.9 GeV.
In all cases we observe a huge low-mass enhancement in the σ-channel of the ππ invariant mass distribution. This enhancement at the ππ threshold is much larger than anticipated from previous inclusive measurements, accompanied with the excitation of a ΔΔ intermediate system, however, not accompanied with a high-mass enhancement as speculated previously. It points to a strong attractive interaction in the ΔΔ system, may be even to the formation of a bound state. Such an assumption leads to a quantitative description of the inclusive data on dd→ 4He X, too.
Exclusive data on the latter reaction will be provided by the analysis of the last WASA run at CELSIUS as well as by measurements at WASA@COSY.
* supported by BMBF (06 TU 261), DFG (Europ. Grad. School), COSY-FFE