Parity Violation in Polarized Electron Scattering

Parity violation has been well established in particle physics for many years, since the 1950's where it was. first seen in beta decay processes. The strong and electromagnetic forces are parity conserving, and the experimental evidence that parity was not conserved in weak processes came somewhat as a surprise. The weak forces are responsible for the decay of radioactive nuclei, and it was in these decay processes where parity non-conservation was first observed. Beta decay occurs through emission of e+ or eparticles, indicating that the weak force can carry charge of both signs, and it was natural to speculate on the existence of a neutral component of the weak force. Even though weak neutral forces had not been observed it was conjectured that a neutral component of weak decay could exist, and Zel'dovichl in 1957 suggested that parity violating effects may be observable in electron scattering and in atomic spectra.