Search for direct CP violating charge asymmetries in K ± → π ± π + π − and K ± → π ± π 0 π 0 decays

A measurement of the direct CP violating charge asymmetries of the Dalitz plot linear slopes Ag = (g + − g)/(g + g) in K → πππ and K → πππ decays by the NA48/2 experiment at CERN SPS is presented. A new technique of asymmetry measurement involving simultaneous K and K beams and a large data sample collected allowed a result of an unprecedented precision. The charge asymmetries were measured to be Ag = (−1.5± 2.1)× 10 with 3.11× 10 K → πππ decays, and Ag = (1.8±1.8)×10−4 with 9.13×107 K → πππ decays. The precision of the results is limited mainly by the size of the data sample. Funded by the U.K. Particle Physics and Astronomy Research Council Present address: Istituto di Cosmogeofisica del CNR di Torino, I-10133 Torino, Italy Present address: Scuola Normale Superiore and INFN, I-56100 Pisa, Italy Present address: CERN, CH-1211 Genève 23, Switzerland Also at Centre de Physique des Particules de Marseille, IN2P3-CNRS, Université de la Méditerranée, Marseille, France Also Istituto di Fisica, Università di Modena, I-41100 Modena, Italy Istituto di Fisica, Università di Urbino, I-61029 Urbino, Italy Present address: Physikalisches Institut, Universität Bonn, D-53115 Bonn, Germany Funded by the German Federal Minister for Education and research under contract 05HK1UM1/1 Permanent address: SLAC, Stanford University, Menlo Park, CA 94025, U.S.A. Present address: UCLA, Los Angeles, CA 90024, U.S.A. Funded by the German Federal Minister for Research and Technology (BMBF) under contract 056SI74 Funded by the Austrian Ministry for Traffic and Research under the contract GZ 616.360/2-IV GZ 616.363/2-VIII, and by the Fonds für Wissenschaft und Forschung FWF Nr. P08929-PHY