content_image/353143.jpg content_image/353142.jpg content_image/353141.jpg content_image/353140.jpg
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 

## A. Direct CP asymmetry in B → X$_{s}$γ 

<img src='content_image/353143.jpg'>

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]. 

<img src='content_image/353142.jpg'>

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] 

<img src='content_image/353141.jpg'>

where 

<img src='content_image/353140.jpg'>

