Determination of lifetimes of 6P_J levels and ground-state polarizability of Cs from the van der Waals coefficient C₆

A method for determination of atomic lifetimes from the value of dispersion coefficient C₆ of molecular potentials correlating to two ground-state atoms is proposed. The method is illustrated with atomic Cs using C₆ deduced from high-resolution Feshbach spectroscopy. The following lifetimes are determined: τ_6P1/2=34.80±0.07 ns and τ_6P3/2=30.39±0.06 ns. The underlying electric-dipole matrix elements are required for a refined analysis of parity violation in ¹³³Cs. We also obtain static polarizability of the Cs ground state, α(0)=400.49(81) atomic units. It is demonstrated that the uncertainties may be considerably reduced as the coefficient C₆ is constrained further.