Double-pionic fusion of nuclear systems and the "ABC" effect: approaching a puzzle by exclusive and kinematically complete measurements.
نویسندگان
چکیده
The ABC effect-a puzzling low-mass enhancement in the pipi invariant mass spectrum, first observed by Abashian, Booth, and Crowe-is well known from inclusive measurements of two-pion production in nuclear fusion reactions. Here we report on the first exclusive and kinematically complete measurements of the most basic double-pionic fusion reaction pn-->dpi;{0}pi;{0} at beam energies of 1.03 and 1.35 GeV. The measurements, which have been carried out at CELSIUS-WASA, reveal the ABC effect to be a (pipi)_{I=L=0} channel phenomenon associated with both a resonancelike energy dependence in the integral cross section and the formation of a DeltaDelta system in the intermediate state. A corresponding simple s-channel resonance ansatz provides a surprisingly good description of the data.
منابع مشابه
The ABC Effect in Double-Pionic Nuclear Fusion and a pn Resonance as its Possible Origin
The ABC effect – a long-standing puzzle in double-pionic fusion – has been reexamined by the first exclusive and kinematically complete measurements of solid statistics for the fusion reactions pn → dππ, pd →Heππ and dd →Heππ using the WASA detector, first at CELSIUS and recently at COSY — the latter with a statistics increased by another two orders of magnitude. In all cases we observe a huge ...
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ورودعنوان ژورنال:
- Physical review letters
دوره 102 5 شماره
صفحات -
تاریخ انتشار 2009