B _s Mixing and $\sin2\Phi_{B_s}$

It is clear from Chap. 2 that the study of CP violation phenomena in$b\to s$ transitions is the current frontier for New Physics search in flavor physics. We have two intriguing hints from the B factories. One is the ${\varDelta S}$ problem, a difference in time-dependent CPV measurement between charmless $b\to s\bar qq$ modes and the established $\sin2\phi_1/\beta$ in $b\to c\bar cs$ modes. But this effect is not experimentally established, and we need to wait for the Super B factory upgrade to clarify the situation. The other hint is the ${\varDelta A}_{K\pi}$ problem, the difference in direct CPV asymmetries in $B^+\to K^+\pi^0$ vs $B^0 \to K^+\pi^-$ decays. Here, the effect is an experimental fact, and indeed it could arise from New Physics CPV through the electroweak penguin amplitude. However, despite the immense challenge it poses to calculational approaches, it is not impossible that the color-suppressed amplitude is enhanced in Nature, in a rather special and major way, to generate ${\varDelta A}_{K\pi}$ in (2.10).