Second‐class currents in beta decay? Available to Purchase

Denys Wilkinson has recently raised again the issue of whether or not second‐class currents exist in the weak interaction. Second‐class currents are defined as having the opposite behavior under G‐parity as first‐class currents. The G‐parity operation is the product of charge conjugation and charge symmetry (which rotates the isotopic spin through 180 deg). Although known to be conserved in strong interactions, G parity might very well not be a useful symmetry for the discussion of weak interactions.