PRECISE MEASUREMENT OF PARITY NONCONSERVING OPTICAL-ROTATION AT 876 NM IN ATOMIC BISMUTH

We report the first precise measurements of parity nonconserving (PNC) optical rotation in atoms, carried out on the 876-nm M1 transition in bismuth. We obtain R(i) = Im(E1PNC(i)/M1) = (-10.12 +/- 0.20) x 10(-8), where E1PNC(i) is the E1 amplitude mixed into the transition by the nuclear spin-independent PNC interaction. The result is in excellent agreement with the standard model of the electroweak interaction. The amplitude of nuclear spin-dependent PNC rotation is found to be less than 1.5 x 10(-2) of that due to the nuclear spin-independent interaction.