HyperCP (E871) Experiment at Fermilab: search for direct CP violation in hyperon decays

The Fermilab HyperCP experiment has accumulated the world's largest sample of Xi (-) and <(<Xi>)over bar>(+) hyperon decays within two running periods in 1997 and 1999. The primary goal of the experiment is to search for dire ct CP <(<Xi>)over bar>(+) --> <(<Lambda>)over bar> pi (+) --> (p) over bar pi (+) pi (+). manifest itself as a difference between the angular distribu tion of the proton and the antiproton in the Lambda and <(<Lambda>)over bar > helicity frame. The amount of data is enough to reach a statistical sensi tivity of 1.4 x 10(-4) in the CP violating asymmetry A(Xi Lambda) = (alpha (Xi) alpha (Lambda) - alpha (Xi) alpha (Lambda))/(alpha (Xi) alpha (Lambda) + alpha (<(<Xi>)over bar>) alpha (<(<Lambda>)over bar>)). We present an an alysis method used to take into A,+ account the slight differences in the p roduction of the Xi (-) and samples. A preliminary result on A(Xi Lambda) a t the level of a few 10(-3) and based on a few percent of the 1997 data wil l be presented.