Beta-alpha angular correlations in mass 8

A detailed study of the ${\beta }^{\mp }-\alpha$ angular correlations in the ${}_{}{}^8{}_{}{}^{}\mathrm{Li}\left({\beta }^{-}\right)$ and ${}_{}{}^8{}_{}{}^{}\mathrm{B}\left({\beta }^{+}\right)$ decays was performed. Since these decays proceed to the $2\alpha$ continuum, detection of both alpha particles enabled determination of various correlations as functions of the final-state energy. The experimental results show a small (≈ 15% of weak magnetism) deviation from the conserved vector current prediction which is dependent on the final-state energy. An effect of this size cannot be interpreted as convincing evidence for the presence of second-class currents or a breakdown of conserved vector current theory. However, the inclusion of the vector second-forbidden terms in the nuclear weak current as predicted by the conserved vector current theory is crucial to obtain even approximate agreement with the experimental results.