Large Effects of CP- and T-Violation in K^0 Decay

Abstract

The epsilon-impurity of the K_L wave-function gives rise to a huge CP-violating effect in the decay K_L -> pi^+ pi^- gamma which is hidden in the polarization state (Stokes vector) of the photon. One component of the Stokes vector is CP-odd and T-even, and may be identified with circular polarization. Another component is CP-odd and T-odd (``oblique polarization'') and reveals itself as a large asymmetry (14%) in the decay K_L -> pi^+ pi^- e^+ e^-. Striking time-dependent effects are predicted in the angular distribution of the pi^+ pi^- e^+ e^- system emanating from an initial K^0 or K^0bar state.