Symmetry of leptons

By assuming that (v e, e−) and (μ+, νμ) belong to the spinor representations θ1/2, 0 and θ0, 1/2 of the rotation group of SU(2)×SU(2), the selection rules for isospin τ and hypercharge s pin ζ are formulated for the pure leptonic processes. As a result, self-current processes such as $$\nu _e \left( {\tilde \nu _e } \right) + e^ - \to \nu _e \left( {\tilde \nu _e } \right) + e^ - $$ belong to the allowed transition, while μ—e exchange processes such as $$\mu ^ \pm \to e^ \pm + \nu _e \left( {\tilde \nu _e } \right) + \nu _\mu \left( {\tilde \nu _\mu } \right)$$ belong to the forbidden transition.