The measurements of Bs parameters in J/psi phi decay mode

Abstract The analysis of the Bs->J/PsiPhi decay is described. The decay constants, GH and GL, and relative contributions of opposite CP-eigenstates, R, can be extracted with polarization (angular) analysis of final states. Good knowledge of these values is necessary for a high precision measurement of a weak phase. Its accuracy can be compromised due to the final states interactions. Time-dependent asymmetry and tagging of initial flavor (at t=0) are the means for simultaneous determination of both, weak and strong, phases.