- Gauge transforms have no effect on measurements, so how can an electroweak SU(2) rotation transform an electron into a neutrino and not be observed?
Most gauge transformations in the standard model are easy to see are measurement invariant. Coordinate transformations, SU(3) quark colours, U(1) phase rotations for charged particles all result in no measurable changes. But how does this work for SU(2) rotations in electroweak theory, where quarks flavours, and electrons and neutrinos, are interchangeable? My guess is that this involves the broken nature of the symmetry and the Higgs field. Is this correct?