The birds and the Bs in RS: the b → sγ penguin in a warped extra dimension

Abstract

Abstract:We calculate contributions to the photon and gluon magnetic dipole operators that mediate b → sγ and b → dγ transitions in the Randall-Sundrum model of a warped extra dimension with anarchic bulk fermions and a brane localized Higgs. Unlike the Standard Model, there are large contributions to the left-handed b quark decays, parameterized by the Wilson coefficient C 7 , due to the pattern of bulk fermion localization, and sizable contributions from the gluonic penguins, C ( ) 8 , through renormalization group mixing. Further, unlike the Randall-Sundrum result for µ → eγ, the unprimed Wilson coefficients receive non-negligible contributions from the misalignment of the bulk fermion spectrum with the Standard Model flavor sector. We compare the size of effects and the constraints imposed by the branching ratios Br(B → X s γ) and Br(B → X d γ) within the minimal and the custodial model. Within the custodial framework, we study the effect on a number of benchmark observables and find that Br(B → X s µ + µ − ) and the forwardbackward asymmetry in B → K * µ + µ − remain close to their Standard Model predictions. On the other hand, there can be large enhancements of the time-dependent CP asymmetry in B → K * γ and the transverse asymmetry A (2)T .

Charming CP violation and dipole operators from RS flavor anarchy

“…At any large but finite β the Higgs overlap with fermion KK modes of high enough KK number starts probing the "bulky" nature of the Higgs and the KK sum converges, as dictated by 5D power counting for a bulk Higgs field. The finiteness of the RS contributions for any β appears to be consistent with the finding of [44].…”

The muon anomalous magnetic moment in the Randall-Sundrum model

“…The 5D framework developed here can be extended to an investigation of lepton and quark flavour-violating radiative processes in warped geometries that goes beyond the approximations adopted in [15][16][17]. We hope to report on such results in the future.…”

“…Substituting this result for b ij into (17) and exploiting the unitarity of the flavour rotation matrices to the mass basis, we obtain…”

Exclusive $$b \rightarrow s \nu \bar{\nu }$$ b → s ν ν ¯ induced transitions in the RS $$_c$$ c model

“…The solution of the equation of motion provides M ++ 2.45 f and M −+ 2.40 f , where f is the dimensionful parameter f = ke −k L . We set this parameter to f = 1 TeV, coherently with other studies [31][32][33].…”