Proton + Proton = Deuterium? How?

[Smarky]

In this Picture: http://upload.wikimedia.org/wikipedia/commons/7/78/FusionintheSun.svg at the beginning, two protons collide and create a Deuterium.
But from the other left-over's we can see that a Beta minus decay has occurred to one of the protons.
So it means that one proton decayed and then collided with the proton?
Or the collision made the proton decay?

 

[Astronuc]

In this Picture: http://upload.wikimedia.org/wikipedia/commons/7/78/FusionintheSun.svg at the beginning, two protons collide and create a Deuterium.
But from the other left-over's we can see that a Beta minus decay has occurred to one of the protons.
So it means that one proton decayed and then collided with the proton?
Or the collision made the proton decay?

The proton transmutation is considered to happen at the time of collision. It's a positron emission with an electron associated neutrion that is emitted via a weak process.

http://hyperphysics.phy-astr.gsu.edu/Hbase/astro/procyc.html#c4

 

[Meir Achuz]

My guess is that those pictures are meant to show why the strong tritium reaction is the dominant one. The d+d reaction requires a photon, so it is EM. The p+p requires a neutrino, so it is weak.