15 have also included in the plot m$_{t}$ ′ = 300 GeV . This is to clarify the fact that the present data on CP asymmetries tends to favor a fourth family of quarks with m$_{t}$ ′ in the range (400 − 600 ) GeV . In this article therefore, we will focus mostly on m$_{t}$ ′ ≈ 400 − 600 GeV when we provide numerical results for SM4 for some interesting observables related to B and K system which could be tested experimentally. A$_{CP}$ in B → X$_{s}$γ is defined as Within the SM, A $^{B}$→X$_{s}$γ CP is predicted to be less than 1% [71–73]. The most recent SM prediction is [74] (Here we have calculated the errors by adding all errors given in the mentioned reference in quadrature ) The current world average of A $^{B}$→X$_{s}$γ CP is ( − 1 . 2 ± 2 . 8)% [52], which is consistent with zero or a very small direct CP asymmetry as we have in the SM. The present experimental uncertainty is still an order of magnitude greater than the theoretical error. However a dramatic improvement in the experimental sensitivity is possible at the upcoming Super-B factories and sensitivity of about 0 . 4% − 0 . 5% can be achieved [75]. As the CP asymmetry within the SM is less than 1%, observation of a sizable CP asym- metry would be a clean signal of new physics. It is expected that the new physics models with non-standard CP-odd phases can enhance A $^{B}$→X$_{s}$γ CP and hence we study A $^{B}$→X$_{s}$γ CP within the framework of SM4. The general expression for the CP asymmetry in B → X$_{s}$γ is [72] where ϵ$_{s}$ = V ∗ $_{us}$V$_{ub}$ V ∗ $_{ts}$V$_{tb}$ , (47) A $^{B}$→X$_{s}$γ CP ≃ 10 − 2 | C tot 7 ( m$_{b}$ ) | 2 { − 1 . 82 Im [ C new 7 ] + 1 . 72 Im [ C new 8 ] − 4 . 46 Im [ C new 8 C $^{new}$∗ 7 ] + 3 . 21 Im [ ϵ$_{s}$ (1 − 2 . 18 C $^{new}$∗ 7 − 0 . 26 C $^{new}$∗ 8 )] } , (46) A $^{B}$→X$_{s}$γ CP | E$_{γ}$> 1 . 6 GeV = ( 0 . 44 +0 . 24 − 0 13 ) % . (45) A $^{B}$→X$_{s}$γ CP = Γ( ¯ B → X$_{s}$γ ) − Γ( B → X$_{¯}$ $_{s}$γ ) Γ( ¯ B X$_{s}$γ ) + Γ( B X$_{¯}$ $_{s}$γ ) (44) A. Direct CP asymmetry in B → X$_{s}$γ