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# In any interaction/decay, how do you know if the particle X that is also produced is watch

1. ...In any interaction/decay, how do you know if the particle X that is also produced is a neutrino or an Anti-neutrino?
For example: pion plus = muon plus + X

Is X anti-neutrino or neutrino and how do you know ?
...In any interaction/decay, how do you know if the particle X that is also produced is a neutrino or an Anti-neutrino?
For example: pion plus = muon plus + X

Is X anti-neutrino or neutrino and how do you know ?
lepton number before = lepton number after

we say that leptons have a lepton number = 1 and anti-leptons = -1

The muon lepton number before is 0 (no muon leptons)

The muon lepton number after = -1 (muon plus is anti-muon)

Therefore, we must add a muon neutrino (+1) to make it zero. so it is a neutrino.
3. (Original post by Kyx)
lepton number before = lepton number after

we say that leptons have a lepton number = 1 and anti-leptons = -1

The muon lepton number before is 0 (no muon leptons)

The muon lepton number after = -1 (muon plus is anti-muon)

Therefore, we must add a muon neutrino (+1) to make it zero. so it is a neutrino.
you can also check baryon number? is there anything else you could check?
4. (Original post by thefatone)
you can also check baryon number? is there anything else you could check?
baryon number does not affect the lepton number, but it would tell you if a baryon is involved

In the above example, baryon number before = 0 (+1/3 for a quark, and -1/3 for an antiquark).

You may also want to check the charge, to find out what charge the particles have after the interaction.

Strangeness is also conserved, but not for weak interactions (decay).
5. (Original post by Kyx)
baryon number does not affect the lepton number, but it would tell you if a baryon is involved

In the above example, baryon number before = 0 (+1/3 for a quark, and -1/3 for an antiquark).

You may also want to check the charge, to find out what charge the particles have after the interaction.

Strangeness is also conserved, but not for weak interactions (decay).
oh ok thanks

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