🚀 go-pugleaf

ric@hpspdla.spd.HP.COM (Ric Peregrino) writes:

>Anyway this simplifies the problem: now only anti-aligned electron
>positron annihilation is possible:

To *two* photons, that's right.

>I was trying to ask about the decay of the positronium from the ground
>state into photons (annihilation). Are their different lifetimes here? I
>think not now, since a spin-aligned positronium has nowhere to decay
>to; there can only be a decay of anti-spin-aligned positronium.

Spin-aligned positronium can decay to final states with
*more* than two photons.  For instance, a three-photon final
state is possible.  This is less likely, so the spin-aligned
state lives longer, but it does decay.
 
-- 
Matt McIrvin, professional gradgrind, amateur Usenet drifter