| Observation of Pontecorvo reactions with open strangeness: (2007) | |||||||||||||
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| We report the first observation of antiproton annihilation on the deuteron into two-body channels with open strangeness. These reactions are of the Pontecorvo type, designating annihilations kinematically not possible on a free nucleon. With antiprotons stopped in a liquid deuterium target, a K 0 S - and # - enriched sample of events, corresponding to about 10 9 annihilations, was recorded with the Crystal Barrel experiment, using a Silicon microstrip detector for triggering on secondary decays. The final states #K 0 S and # 0 K 0 S , with # 0 ###, ##p# - , K 0 S ## + # - , and the equivalent final states #K 0 L and # 0 K 0 L , with noninteracting K 0 L , were identified. The pd branching fraction into #K 0 and # 0 K 0 are (2.35 0.45) 10 -6 and (2.15 0.45) 10 -6 , respectively. This similarity disagrees strongly with two-step model predictions and supports the statistical (fireball) model. Annihilation reactions of antinucleons on atomic nuclei t... | |||||||||||||
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