Breit correction to the parity-nonconservation amplitude in cesium

Including the Breit interaction leads to a 0.6% reduction in the magnitude of the $6s-7s$ parity-nonconservation (PNC) amplitude in ${}^{133}\mathrm{Cs},$ confirming a result recently obtained by A. Derevianko [Phys. Rev. Lett. 85, 1618 (2000)]. A revised value of the theoretical PNC amplitude for ${}^{133}\mathrm{Cs}$ is given; the corresponding value of the weak charge shows no noticeable deviation from the standard model.