Study Of The Rare Hyperon Decay Omega(-/+) -> Xi(-/+)Pi(+)Pi(-)

We report a new measurement of the decay Omega(-) -> Xi(-/+)pi(+)pi(-) with 76 events and a first observation of the decay (Omega) over bar (+) -> (Xi) over bar (+)pi(+)pi(-) with 24 events, yielding a combined branching ratio (3.74(-0.56)(+0.67)) x 10(-4). This represents a factor 25 increase in statistics over the best previous measurement. No evidence is seen for CP violation, with B(Omega(-) -> Xi(-)pi(+)pi(-)) = 4.04(-0.71)(+0.83) x 10(-4) and B((Omega) over bar (+) -> (Xi) over bar (+)pi(+)pi(-)) = 3.15(-0.89)(+1.12) x 10(-4). Contrary to theoretical expectation, we see little evidence for the decays Omega(-) -> Xi(*0)(1530)pi(-) and (Omega) over bar (+) -> (Xi) over bar (*0)(1530)pi(+) and place a 90% C.L. upper limit on the combined branching ratio B(Omega(-)((Omega) over bar (+)) -> Xi(*0)(1530))pi(-/+)) < 7.0 x 10(-5). (C) 2010 Elsevier B.V. All rights reserved.