The Light Quark Sector, CP Violation, and the Unitarity Triangle

Abstract

In view of the observed strong hierarchy of quark masses, we propose a new description of flavor mixing which is particularly suited for models of quark mass matrices based on flavor symmetries. The necessary and sufficient conditions for CP violation are clarified. The emergence of CP violation is primarily linked to a large phase difference (near 90^{\circ}) in the light quark sector. The unitarity triangle is determined by the mass ratios of the light quarks. We conclude that the unitarity triangle should be close or identical to a rectangular triangle, and CP violation is maximal in this sense. Instructive predictions for flavor mixing angles and CP-violating parameters, which can directly be confronted with the forthcoming data from B-meson factories, are obtained from a specific texture of quark mass matrices.