Enhanced KL to pi0 nu nubar from Direct CP Violation in B to K pi with Four Generations

Abstract

Recent CP violation results in B decays suggest that Z penguins may have large weak phase. This can be realized by the four generation (standard) model. Concurrently, B to Xs l+ l- and Bs mixing allow for sizable Vt&#39;s* Vt&#39;b only if it is nearly imaginary. Such large effects in b to s transitions would affect s to d transitions, as kaon constraints would demand Vt&#39;d different from zero. Using Gamma(Z to b bbar) to bound |Vt&#39;b|, we infer sizable |Vt&#39;s| < |Vt&#39;b| < |Vus|$. Imposing epsilon_K, K+ to pi+ nu nubar and epsilon&#39;/epsilon constraints, we find Vt&#39;d* Vt&#39;s = few x 10^(-4) with large phase, enhancing KL to pi0 nu nubar to 5x10^(-10) or even higher. Interestingly, Delta_mBd and sin(2PhiBd) are not much affected, as |Vt&#39;d* Vt&#39;b| << |Vtd* Vtb| = 0.01.