A measurement of parity non-conserving optical rotation in atomic lead

Abstract

We report a measurement of parity non-conserving (PNC) optical rotation in the vicinity of the 1.279 magnetic dipole transition in atomic lead. We obtain a value for the conventional parameter, , with limits on the nuclear spin-dependent contribution set by the anapole constant . The experimental results, when combined with the relevant atomic calculations, lead to a value for the mass of the boson or, alternatively, place a limit on physics beyond the standard model through the isospin-conserving parameter, S.