TOP QUARK MASS AND THE FOURTH GENERATION OF QUARK

To explain CP violation in Kaon system in the light of the recently measured b - lifetime within the framework of three generations of quarks, the top quark mass has to be greater than 50GeV if the current algebra value of the factor B_K is adopted and | ε’/ε|< 0.01. In this letter a fourth generation of quark is considered which can fit the present experimental data on CP violation, and K_L→ μ ⁺ μ^- decay rate for top quark mass is around 40GeV. The mass of the new charge 2/3 quark is predicted to be over 100Gev.