I don’t. That’s why I wrote: > But this would require that when X' and ¬X annihilate each other, the extra momentum of X' is also annihilated. Intuitively, I’d

I don’t. That’s why I wrote: > But this would require that when X' and ¬X annihilate each other, the extra momentum of X' is also annihilated. Intuitively, I’d expect it to be sent out as a photon – with momentum p_ν. I.e. annihilation of the extra momentum would be required for this to work on the basis of background fluctuations (in my understanding), but I don’t think that this happens.