Determination of Re(ɛ’/ɛ) by the simultaneous detection of the fourKL,S→ππ decay modes

The E731 experiment at Fermilab has searched for direct CP violation in ${\mathit{K}}^0$→ππ, which is parametrized by ɛ’/ɛ. For the first time all four of the ${\mathit{K}}_{\mathit{L},}$S→ππ modes were collected simultaneously, which greatly facilitated studies of systematic uncertainty. We find Re(ɛ’/ɛ)=-0.0004±0.0014(stat)±0.0006(syst). The result provides no evidence for direct CP violation.