# I Momentum in proton chain

1. Jul 9, 2017

### Aidan Davis

In the proton chain, a deuteron and proton fuse to make a nucleus of helium 3, releasing 5.493 MeV by E=mc^2. To have the same total momentum before and after fusion, at least two particles must be emitted, right? That way they can "cancel out" some momentum by having roughly opposite directions. So is there some photon or neutrino that I'm leaving out?

2. Jul 9, 2017

### NFuller

Yes, a photon is also emitted.