Parity conservation in atoms: Testing Laporte's rule

Abstract

There are two independent reasons to expect the existence of a new type of weak interaction, involving elastic scattering of electrons and nucleons, e+N→e+N. One is the successful development of unified theories of weak and electromagnetic interactions, based on isospin multiplets of leptons, hadrons and vector mesons. The other is the experimental discovery of the elastic scattering of high energy neutrinos from nucleons, ν+N→ν+N. Together, these developments provide strong motivation to the search for weak electron-nucleon interactions in ordinary atoms, through a breakdown of Laporte's rule. I will present a review of recent developments in this field, including a qualitative discussion of this type of weak interaction and a short summary of the experiments in progress. I will also give a more detailed discussion of one particular experiment at Michigan, involving microwave transitions in a metastable hydrogen beam.