Parity Violation in Atoms

Abstract

The purpose of this talk is to give a concise review of experiments searching for parity violation (PV) in atoms [1] (time-reversal invariance being assumed). Stress will be laid on guiding principles rather than on technical details. Due to lack of time, we are going to concentrate on those proposals which, to our knowledge, have materialized in actual experiments now completed. In practice we will leave aside the microwave experiments on hydrogen, deuterium and He which are in progress [2] and only discuss experiments on heavy atoms (HA). Furthermore we will concentrate on the recent experiments [3,4] on cesium for the following reasons: i) at present they constitute the only case of uncontested agreement between measurements performed by different groups using different methods; ii) they are now approaching the precision (<10%) of the best high-energy tests of the electroweak theory; iii) experimental results can be reliably interpreted in an atom as simple as cesium. In fact, quite different approaches obtain consistent results within the theoretical uncertainty which is now lowered down to 5% [5–8].