I'm not very familiar with this topic so I quickly went through some introductory books on nuclear physcis and read the chpater about beta decay. What I don't understand looking at this graph is the following:
Why is the direct decay to ground state absolutely forbidden ? If you take a 1st order forbidden transition with ##l = 3##, then parity can change and conservation of angular momentum can be assured by requiring the electron and neutrino to have opposite spin (S = 0). Yet you don't see this.
An other question I have is: are EC selection rules the same ones I have in ##\beta##-decay? (I have zero background in nuclear physics so I apologize if my question is stupid)