R. Adler et al., FIRST OBSERVATION OF A PARTICLE ANTIPARTICLE ASYMMETRY IN THE DECAY OF NEUTRAL KAONS INTO PI(0)PI(0), Zeitschrift fur Physik. C, Particles and fields, 70(2), 1996, pp. 211-217
CP violation has been observed as a time-dependent rate asymmetry betw
een the decays <(K)over bar (0)> --> pi(0) pi(0) and K-0 --> pi(0) pi(
0), where the neutral kaons are produced with definite and individuall
y known strangeness in <(p)over bar p> --> <(K)over bar (0)> K(+)pi(-)
or <(p)over bar p> --> K(0)K(-)pi(+). A special technique for the dat
a analysis has been developed. The values obtained for phi(00) and \et
a(00)\ are in agreement with those of previous measurements of CP viol
ation.