Observation of a parity violation in cesium

We have measured a parity violation in the 6S–7S transition of Cs in an electric field. Our result is Im $\text{E}{}_1{}^{\mathrm{<mtext>pv</mtext>}}\text{β}\text{= -1.34 ± 0.22}$$\text{(}\text{rms statistical deviation}\text{) ± ～0.11 (}\text{systematic uncertainty}\text{)}\text{mV}\text{cm;}\text{E}{}_1{}^{\mathrm{<mtext>pv</mtext>}}$ is the parity violating electric dipole amplitude, ß is the vector polarizability. This result is consistent with the Weinberg-Salam prediction.