CP Violation in B Meson Decays

Recent CP asymmetry measurements in tree-dominated processes, B0→π+π−,ρ+ρ−,ρ±π∓, B+→DK+, and in penguin-dominated decays, B→π0KS,η′KS,ϕKS, are interpreted in the framework of the Kobayashi-Maskawa (KM) mechanism of CP violation. The KM phase emerges as the dominant source of CP violation in tree-dominated decays, which are beginning to constrain the unitarity triangle beyond other constraints. Improving precision of CP asymmetry measurements in penguin-dominated decays may indicate the need for new physics.