Relative Sign of Strangeness-Changing Axial-Vector and Vector Currents

Abstract

The determination of the relative sign of strangeness-changing hadronic axial-vector and vector currents is considered within the framework of $V$, $A$ theory and the experimental information on hyperon beta decays, in particular the spin correlation parameters for $\ensuremath{\Lambda}\ensuremath{\rightarrow}\mathrm{pe}\ensuremath{\nu}$. If the sign of the $\ensuremath{\Lambda}$ polarization is accepted as obtained from nonleptonic decay experiments, the $V+A$ form of the current is excluded. If the polarization sign is assumed to be the opposite, a necessary condition for the consistency of the correlation parameters for $\ensuremath{\Lambda}\ensuremath{\rightarrow}\mathrm{pe}\ensuremath{\nu}$ with $V$, $A$ theory is the presence of very large tensor and/or axial-tensor form factors. Explicit fits to the data allowing for such form factors have very small probabilities. It is concluded that the consistency of the experimental results with $V$, $A$ theory strongly supports the polarization sign as inferred from $\ensuremath{\Lambda}\ensuremath{\rightarrow}p\ensuremath{\pi}$, and hence, the $V\ensuremath{-}A$ form of the $|\ensuremath{\Delta}S|=1$ current.