# Antimuon and electron annihilation to 2 photons [closed]

An antimuon and electron may bind together via Coulombic attraction and then decay, but is the following process possible? $$(\mu^++e^-) → \gamma + \gamma$$

$$\mu^+$$ : antimuon

$$\gamma$$ : photon

$$e^-$$ : electron

Which of the following claims are correct?

a) This decay mode can proceed naturally.

b) This decay would violate electron-lepton number. $$0 + 1 (e) \rightarrow 0 + 0$$

c) This decay would violate muon-lepton number. $$-1(\mu^+) + 0 \rightarrow 0 + 0$$

d) This decay would violate tau-lepton number. $$0 + 0 \rightarrow 0 + 0$$

e) This decay would violate charge conservation. $$+1 - 1 \rightarrow 0 + 0$$

The antimuon has a lepton number of -1. The electron has a lepton number of +1. So lepton number isn't violated - that takes out b) c) d).

I thought annihilation had to occur with a particles respective antiparticle. i.e. electron-positron, etc. Meaning a) is also not correct.

Charge of the electron is -1, and antimuon is +1. therefore charge would be conserved - ruling out e)

Of all my assumptions here a) is the only one I'm not too sure about.

• Lepton numbers of each kind are conserved separately. Also, I'm not very sure what those 5 points are... Are they general claims? Options in an MCQ? But the decay mode won't proceed, and points (d) and (e) are false. – user191954 Jul 18 '18 at 11:53
• Yes, sorry it's a MCQ. – says Jul 18 '18 at 13:20
• Are you supposed to isolate 1 of those 5 claims which is wrong, or 1 which is right, or something else? Because unless I'm severely confused, both c and d are correct, but a, d, and e are incorrect propositions... – user191954 Jul 18 '18 at 13:24
• No, there's more than one correct answer. So in this case I'd say it's b) and c) – says Jul 18 '18 at 13:25
• – Bert Barrois Jul 18 '18 at 18:58