# Allowed Reactions

1. Nov 16, 2007

### genloz

I would really just like to know if I'm on the right track here in terms of if reactions can go ahead or not... The reactions are in latex and my thoughts are below each one..
1. The problem statement, all variables and given/known data
For each of the following processes say whether it is a strong, electromagnetic or weak process or whether it is forbidden in the standard model and explain the reasons.

Process 1
$$K^{0} \rightarrow \pi^{+}+e^{-}$$
Charge conserved
Mass conserved
Lepton Number - not conserved
Baryon Number - no baryons
Spin - (-1/3)(1/3) -> (2/3)(1/3) + (1/2) not conserved
Strangeness - not conserved
Therefore not possible
It would have been a weak interaction though?

Process 2
$$e^{-}+p \rightarrow n+\upsilon_{\mu}$$ (the final thing should be a muon neutrino)
Charge conserved
Mass conserved
Lepton Number - not conserved
Baryon Number - conserved
Spin - (1/2) + (1/2) -> (1/2) + (0) not conserved
Strangeness - conserved
Therefore not possible
It would have been a weak interaction though?

Process 3
$$\Delta^{0} \rightarrow \pi^{+}+n$$
Charge conserved
Mass conserved
Lepton Number - no leptons
Baryon Number - conserved
Spin - ???? -> 0 + (1/2) no idea
Strangeness - conserved
Therefore possible? (dependent on spin)
It would be a weak interaction

Process 4
$$K^{0} + n \rightarrow \Lambda + \pi^{0}$$
Charge conserved
Mass conserved
Lepton Number - no leptons
Baryon Number - ????????
Spin - ??????????
Strangeness - not conserved (s in the K, anti-s in the lambda)
Therefore possible? (dependent on spin & baryon number)
It would be a weak interaction

Process 5
$$\Xi^{0} \rightarrow \Lambda + \pi^{0}$$
Charge conserved
Mass conserved
Lepton Number - no leptons
Baryon Number - ????????
Spin - ??????????
Strangeness - not conserved (ss in the Xi, s in the lambda)
Therefore possible? (dependent on spin)
It would be a weak interaction

Also, In what situation would it be a strong interaction?

2. Nov 16, 2007

### genloz

Actually, I think processes 3,4 and 5 are strong interactions rather than weak...

3. Nov 16, 2007

### genloz

Okay, process 3 also isn't possible due to the delta having spin 3/2, the pion having spin 0 and the neutron having spin 1/2 so this is also impossible due to spin not being conserved?

Process 4
Baryon Number 0 + 1 -> 1 + 0, conserved
Spin 0 + 1/2 -> 1/2 + 0, conserved
So process 4 is possible...

Process 5
Baryon Number 1 -> 1 + 0 conserved
Spin - can't find out the spin for Xi, -> 1/2 + 0
So it's not possible due to lack of strangeness conservation and possibly spin but unsure on this point??

Please let me know if I'm on the right track here!