Rare B Decays In The F-SU(5) Model

Thanks to the eforts of the B factories and Large Hadron Collider （LHC）,the exploration of quark-flavor mixing is now entering a new interesting era. Itis well known that the rare B decays induced by the flavor changing neutralcurrent （FCNC） only occur at loop level in the Standard Model （SM） and thenare sensitive to new physics.String theory is the most promising candidate for quantum gravity, and it canunify all the fundamental interactions in the Nature. However, the string scaleis at least one-order larger than the conventional GUT scale. Testable FlippedSU（5）×U（1）_Xsolve the little hierarchy problem between the traditional GUTscale and string scale and realizes the string scale gauge coupling unification.In the testable Flipped SU（5）×U（1）Xmodel F-SU（5） model) with TeV-scale vector-like particles, we study the vector-like quark contributions to Bphysics processes, including the quark mass spectra, Feynman rules, new opera-tors and Wilson coefcients, etc. We focus on the implications of the vector-likequark mass scale on B physics. We find that there exists the s|-bZ interaction attree level, and the Yukawa interactions are changed.In B physics, the most commonly used methods are the expansion of operatorand the running of coupling coefcient.We find:1) the efects of vector-like quarks on rare B decays such asBâ†'Xsγ and Bâ†'Xsl+l do not decouple in some viable parameter space,especially when the vector-like quark masses are comparable to the charged Higgsboson mass;2)Under the constraints from Bor Bâ†'Xsγ and Bâ†'Xsl⁺l^-, thelatest measurement for Bsâ†'μ⁺μ^-can be explained naturally;3)the branchingratio of Bsâ†'l⁺l^-γ can be up to （4～5）×10^-8. The non-decoupling efects aremuch more predictable and the branching ratio of Bsâ†'l⁺l^-γ may be tested atLHCb.