Some remarks on parity violating effects of intramolecular interactions

Summary

The role of the parity violating weak interaction in atomic and molecular physics is pursued. Parity violating forces do in fact distinguish between molecular configurations which are identical up to a space reflection as is assumed to be the case for optical isomers. The corrections to the binding energies of such molecules are, however, tiny. In conventional weak interaction theory this is due to the gauge invariance of the photon mediating electromagnetic forces between electrons and electrons and between electrons and nucleons. The constraint of gauge invariance does not allow for long range parity violating forces of first order in the weak coupling constant G. This implies that parity violating effects in atoms or molecules are suppressed not only by a factor of ≲ 10⁻⁵ due to the smallness of the weak coupling constant but also by the ratio of the range of parity violating forces divided by the average extension of the electron cloud which is in addition at most of order ≲ 10⁻⁵. Therefore no appreciable energy difference between optical isomers is expected within the framework of conventional weak interaction.