Correlation effects in the parity-nonconserving6s→7stransition in cesium

The amplitude of the parity-nonconserving (PNC) electric-dipole transition 6s{→}7s in cesium is calculated to third order in many-body perturbation theory. Inclusion of the corresponding corrections in calculations of parity-conserving transition amplitudes and atomic hyperfine constants leads to agreement with experiment at a level under 5%. We obtain a value of 0.951iea₀×{}10^-11{Q}W$/-N with an estimated error of 5% for the PNC amplitude. A determination of the Weinberg angle is made by combining the present calculation with recent measurements of the PNC amplitude: the result is sin²{{{θ}}}W$=0.229 ${(24)}ₑₓₚₜ$ ${(16)}ₜₕₑₒᵣ$. Issues involved in improving the accuracy of the calculations of atomic properties of cesium are discussed.