CP Violation in Λ_b → Λł⁺ł^-Decay in the Four–Generation Standard Model

We present the first study of CP asymmetry in Λ_b →Λ decay when a new weak phase comes through the extension of three-generation standard model to the four-generation standard model. Taking =0.01,0.02,0.03 with phase 60°-120°, which is consistent with therate and the Bs mixing parameter ΔmBs, we find out that CP asymmetry is quite sensitive to the existence of fourth generation. It can serve as a good tool to search for new physics effects, in particular, to search for the fourth generation quarks (t', b') via their indirect manifestations in loop diagrams.