Search for Parity-Nonconserving Optical Rotation in Atomic Bismuth

We report the results of a laser experiment to search for the parity-nonconserving optical rotation in atomic bismuth. We work at wavelengths close to the 648-nm $J=\frac{3}{2}$ — $J=\frac{5}{2}$ $M_1$ transition from the ground state. We find $R=\mathrm{Im}\left(\frac{E_1}{M_1}\right)=(+2.7\mathrm{}\pm 4.7)\times {10}^{-8\mathrm{}}$, in disagreement with the theoretical value $R=-30\mathrm{}\times {10}^{-8\mathrm{}}$ predicted for this transition on the basis of the Weinberg-Salam model of the weak interactions combined with relativistic central-field atomic theory.