PARITY VIOLATION IN FEW-NUCLEON SYSTEMS: WHERE DO WE STAND?

Abstract

We review the present status of our understanding of parity violation in few-nucleon systems. At low energies, nuclear parity-violating forces can be parametrized in the framework of meson-exchange potentials. The pertinent weak meson-nucleon couplings can be calculated by invoking either the quark or the soliton model of the low-lying baryons. We compare the resulting couplings and discuss the advantages and limitations of both approaches. Then, we turn to the experimental study of nuclear parity violation in few-nucleon systems. First, we review various calculations of the longitudinal asymmetry in proton-proton scattering with an eye on the upcoming high-precision experiment at TRIUMF. We stress the importance of a consistent calculation of the weak and strong nucleon-nucleon potential. A toy calculation is presented for the photo-disintegration of the dueteron, which appears to be an excellent candidate to pin down the parity-violating pion-nucleon coupling constant. We encourage further theoretical as well as experimental studies.