Parity violation in atoms

In atomic physics, the parity violation is the only way to distinguish the effect of weak interaction from the largely dominant electromagnetic interaction effect. Experiments using heavy atoms, in particular cesium atoms for which the effect of weak interaction is more important, and on forbidden transitions where the electromagnetic interaction effect is reduced, have allowed the measurement of a transition amplitude that violates parity. Available precise atomic physics calculations allow to bound this amplitude with the weak charge of the nucleus predicted by weak interaction theories and in particular by the standard model. These informations obtained at very low energies (about 1 keV) about the weak interaction in the electron-hadron sector are complementary to those obtained from great accelerator experiments. The measurements of radiative corrections at weak charge or dependant from nuclear spin can provide additional information, on condition that experiments can reach the calculations precision (1 %). The experiments in progress are described, in particular the one developed at the ENS (Ecole Normale Superieure de Paris). (J.S.). 45 refs., 19 figs