Calculations of parity-nonconserving s-d amplitudes in Cs, Fr, Ba+, and Ra+ -: art. no. 062101

We have performed ab initio mixed-states and sum-over-states calculations of parity-nonconserving (PNC) electric dipole (E1) transition amplitudes between s-d electron states of Cs, Fr, Ba+, and Ra+. For the lower states of these atoms we have also calculated energies, E1 transition amplitudes, and lifetimes. We have shown that PNC E1 amplitudes between s-d states can be calculated to high accuracy. Contrary to the Cs 6s-7s transition, in these transitions there are no strong cancellations between different terms in the sum-over-states approach. In fact, there is one dominating term which deviates from the sum by less than 20%. This term corresponds to an s-p(1/2) weak matrix element, which can be calculated with an accuracy of better than 1%, and a p(1/2)-d(3/2) E1 transition amplitude, which can be measured. Also, the s-d amplitudes are about four times larger than the corresponding s-s amplitudes. We have shown that by using a hybrid mixed-states-sum-over-states approach the accuracy of the calculations of PNC s-d amplitudes could compete with that of Ca 6s-7s if p(1/2)-d(3/2) E1 amplitudes are measured to high accuracy.