{\it Ab initio} studies of electron correlation effects in the atomic parity violating amplitudes in Cs and Fr

We have studied the correlation effects in Cs and Fr arising from the interplay of the residual Coulomb interaction to all orders and the neutral weak interaction which gives rise to the parity violating electric dipole transition to first order, within the framework of the relativistic coupled-cluster theory which circumvents the constrain of explicitly summing over the intermediate states. We observe that, the contributions arising from the perturbed doubly excited states are quite significant and hence, any calculation should not be considered accurate unless it includes the perturbed double excitations comprehensively. In this article, we have reported a comparative study of various results related to the parity violation in Cs and Fr.Comment: 8 pages, 3 tables, 3 figure

Nuclear quadrupole moment of 43Ca and hyperfine structure studies of its singly charged ion

By combining our theoretical calculation and recently measured electric quadrupole hyperfine structure constant of the $3d ^2D_{5/2}$ state in the singly ionized $^{43}$Ca, we determine its nuclear quadrupole moment to one percent accuracy. The obtained result, $-0.0444(6)b$, is about ten percent improvement over the considered standard value. We have employed the relativistic coupled-cluster theory at single and double excitations level to calculate the electronic wave functions. The accuracy of these wave functions are estimated by comparing our calculated magnetic dipole hyperfine constants with their corresponding available experimental results of many low-lying states. We also present hyperfine structure constants for other higher excited states where experimental results are not reported. Role of the Breit interaction has been investigated in these properties.Comment: 7 pages, 7 table