Conserved Vector Current Hypothesis (CVC)

[man@SUT]

What is it and how does it connect to weak interaction and electromagnetic interaction? I read from some webs, it is proposed from the isospin ladder operator. But in the book (Griffiths), he doesn't say anything about isospin ladder operator but he produces from the decay of neutron or beta decay(another book). May it come form the same thing?

man@SUT

 

[Perturbation]

As in the Noether current associated with some symmetry?