Probing New Physics From CP Violation in Radiative B Decays

When new CP-violating interactions are dominated by flavor changing neutral particle exchanges, that may occur in many extensions of the standard model. We examine a type 3 two Higgs doublet model and find that direct CP asymmetries can be as large as about 25% . Time-dependent and time-integrated mixing-induced CP asymmetries up to 85 and 40 %, respectively, are possible without conflict with other constraints. It mainly requirs an enhanced chromo-magnetic dipole b → sg decay to be close to the present experimental bound. PACS numbers: 11.30.Er 12.60.Fr 13.25.Hw 13.40.Hq The CP-averaged radiative exclusive decay B → K+γ [1] and inclusive decay B → Xs+γ [2] represent the first observation of electromagnetic penguins. The CP-averaged branching ratios are consistent at the 2σ level with those [3] expected from a loop involving a top quark and W boson in the standard model (SM). Within the present uncertainties from both experimental measurements and theoretical calculations, it is difficult, only from the CP-averaged branching ratios, to distinguish the differences between the uncertainties and new physics effects. However, it does not mean that contributions to the amplitudes from new physics are less important than the one from the SM. This is because, if there exist new interactions involving new CP-violating sources, the magnitude of the amplitude A EMP from new CP-violating interactions can become comparable with or even larger than the one A EMP from the SM even when radiative decay rate measurements are roughly that expected from the SM. This happens when the contributions to the radiative decay rate from the interference term 2Re(A EMPA NEW∗ EMP ) almost cancel with the one |ANEW EMP |2, i.e., |ANEW EMP |2 ≃ −2Re(ASM EMPA EMP ). This shows that as long as the relative phase between the two amplitudes ranges from about (2π/3) to (4π/3), |ANEW EMP | will become larger than |ASM EMP |. In this case, it will be alternatively interesting