Reconciliation of experimental and theoretical electric tensor polarizabilities of the cesium ground state

– We present a new theoretical analysis of the strongly suppressed F-and M-dependent Stark shifts of the Cs ground state hyperfine structure. Our treatment uses third order perturbation theory including off-diagonal hyperfine interactions not considered in earlier treatments. A numerical evaluation of the perturbation sum using bound states up to n=200 yields ground state tensor polarizabilities α2(6S 1/2 , F) which are in good agreement with experimental values, thereby bridging the 40-year-old gap between experiments and theory. We have further found that the tensor polarizabilities of the two ground state hyperfine manifolds have opposite signs, in disagreement with an earlier derivation. This sign error has a direct implication for the precise evaluation of the blackbody radiation shift in primary frequency standards. Introduction. – Since its discovery, the Stark effect, i.e., the interaction of an atom with an external electric field E, has played an important role in the spectroscopic investigation of atomic structure. Because of parity conservation, the Stark effect arises only in second order perturbation theory for atoms with non-degenerate orbital angular momentum states. The energy shift ∆E(γ) of a magnetic sublevel |γ = |nL J , F, M of the hyperfine structure is conventionally parametrized in terms of a polarizability α(γ) as