Search for a parity violation induced by neutral currents in the 6S–7S transition of atomic cesium

Parity violating, time-reversal invariant, weak neutral currents can induce an electric dipole transition moment, E₁^p.v., between atomic states of same parity. We report here on the preliminary results of an experiment designed to measure E₁^p.v. in the 6S–7S transition of atomic cesium, using a polarization effect characteristic of the interference of E₁^p.v. with the electric dipole transition moment E₁^ind. induced by a d.c. electric field. At a 90% confidence level we find the upper limit: |E₁^p.v.| < 2.0 × 10^?9|e|a₀. As a consequence the coupling constant of the electron-nucleon interaction involving the product of an axial electronic neutral current by a vector nucleonic one must be less than 44 G_F.