Nonspectator effects in B-> K*+photon within the vector quark model

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The tree level FCNC due to the presence of an additional generation of vector quarks result in the leading order nonspectator contributions to rare B-> K*+photon decay mode. These tree level contributions are sensitive only to b-> s nonunitary parameter Usb and therefore, provide a direct constraint on this model parameter. We obtain the isospin asymmetry between B⁰-> K*⁰+photon and B--> K*⁻+photon to be Δ₀₋=-0.03*Re (Usb/(aᶜ₇VtbV*ts)) and the direct CP asymmetry between B+->K*⁺+photon and B--> K*⁻+photon to be ACPVQM=0.27|Usb/(VtbVts*)|*sinθ*sinϕₛ, where θis the weak phase of Usb and ϕₛ is the strong phase of decay amplitude. We predict a direct CP asymmetry of around a few percent if the current experimental difference between Δ₀₋ and Δ₀₊ is to be explained by the presence of the additional vector quarks.