Fock-space perturbed relativistic coupled-cluster calculations of electric dipole polarizability and nuclear spin-dependent parity non-conservation in Cs

We implement the Fock-space perturbed relativistic coupled-cluster theory to compute the electric dipole polarizability of ground and low lying excited states, and nuclear spin-dependent parity violating transition amplitudes in Cs. Moreover, to check the accuracy of the wavefunctions used in the calculations, we compute the excitation energies, E1 transition amplitudes and magnetic dipole hyperfine constants for ground and low lying excited states. To improve the accuracy of the computed properties, we have incorporated the corrections from the relativistic and QED effects in our calculations. The contributions from triple excitations are accounted perturbatively. Our results on excitation energies, E1 transition amplitudes and hyperfine constants are in good agreement with the experimental results. Our polarizability results using FS-PRCC theory are in good agreement with the experimental data. Our values of parity-violating transition amplitudes are, in general, on the lower side of the previous values. From the analysis of the electron correlations, we find that the corrections from the Breit interaction and QED effects are important to get accurate results of nuclear spin-dependent parity-violating transition amplitudes in Cs. The largest cumulative contribution from Breit and QED corrections is found to be $\approx$ 3.2\% of the total value. The upper bound on the theoretical uncertainty in our calculated parity violating transition amplitudes is estimated to be about 1\%.