KL→π0l+l− decays for large mt

Abstract

We discuss the decays $K_L$→${\pi }^0$ $l^{+}$ $l^{\mathrm{-}}$ when $m_t$ is large. Unlike the case of $K_L$→ππ, CP violation in the decay amplitude itself is comparable to that which comes from the mass matrix. We study the CP-violating effects, including strong-interaction (QCD) corrections to the amplitudes which arise from one-loop diagrams. Short-distance contributions from diagrams that involve a W and a Z or two W’s as well as from those with a photon and a W are important when $m_t$≳$M_W$.