Breit interaction and parity nonconservation in many-electron atoms

We present accurate ab initio nonperturbative calculations of the Breit correction to the parity nonconserving (PNC) amplitudes of the $6s\text{−}7s$ and $6s\text{−}5d_{3∕2}$ transitions in Cs, $7s\text{−}8s$ and $7s\text{−}6d_{3∕2}$ transitions in Fr, $6s\text{−}5d_{3∕2}$ transition in ${\mathrm{Ba}}^{+}$, $7s\text{−}6d_{3∕2}$ transition in ${\mathrm{Ra}}^{+}$, and $6p_{1∕2}\text{−}6p_{3∕2}$ transition in Tl. The results for the $6s\text{−}7s$ transition in Cs and $7s\text{−}8s$ transition in Fr are in good agreement with other calculations. We demonstrate that higher-orders many-body corrections to the Breit interaction are especially important for the $s\text{−}d$ PNC amplitudes. We confirm good agreement of the PNC measurements for cesium and thallium with the standard model.

Figure 1

Second-order correlation potential $\widehat{\Sigma }(r_1,r_2)$. Left arrows denote core states, right arrows denote states above the core, waved line is the sum of Coulomb and Breit interactions.