Double lepton polarization in Λb→Λℓ+ℓ−Λb→Λℓ+ℓ− decay in the Standard Model with fourth generations scenario

This study investigates the influence of the fourth generation quarks on the double lepton polarizations in Λb→Λℓ+ℓ−Λb→Λℓ+ℓ− decay by taking |Vt′s*Vt′b|=0.005,0.01,0.02,0.03 with phase {60°,90°,120°}{60°,90°,120°}. We will try to obtain a constrain on the mass of the 4th generation top like quark t′t′, which is consistent with the b→sℓ+ℓ−b→sℓ+ℓ− rate. With the above mentioned parameters, we will try to show that the double lepton (μ,τ) polarizations are quite sensitive to the existence of fourth generation. It can serve as a good tool to search for new physics effects, precisely, to search for the fourth generation quarks (t′,b′t′,b′) via its indirect manifestations in loop diagrams.