ar X iv : h ep - p h / 95 03 21 8 v 1 3 M ar 1 99 5 The Effects of Flavor Changing Neutral Current and
نویسنده
چکیده
We study the effects of tree-level flavor changing neutral current and its present status with Cabibbo-Kobayashi-Maskawa matrix. Especially, we remark the effects of flavor changing neutral current on the unitary triangle of Cabibbo-Kobayashi-Maskawa matrix. In the case when the unitarity is nearly conserved, we find that the allowed FCNC in the db sector is zd db /V CKM td V CKM tb * ∼ O(10 −2), from the evaluation of the present bounds for the mixing size of neutral B meson (x d), and the CP violation parameter in the neutral K meson (ǫ). Although the size is small, the new physics due to the tree-level FCNC in the db sector is expected to be visible in the B → X d l + l − and the CP asymmetries in the neutral B meson system. In the case when the unitarity is violated and the quadrangle is conserved, the FCNC is large enough, i.e. zd db /V CKM td V CKM tb * ∼ O(1). Then, a significant contribution is also expected in the inclusive B → X d γ decay. As a typical model with this charateristic, we consider Vetor-like Quark Model, where the vector-like quarks are added into the three standard generations of quarks. An overview of the flavor physics in the SM is also given.
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