eli5 where does the neutron come from when creating helium in fusion?

Question

I keep seeing things about how protons turn into neutrons but that makes no sense to me. How can the quarks of a proton seemingly change and turn into a neutron? I have a project and I need to know this for both neutron stars and nuclear fusion

In: 3

Answer 1

Basically, for some really weird reason, if I remember correctly from my astronomy classes, the weak interaction turns one of the proton’s (up) quarks the other way creating a down quark creating a neutron,you could also use electrons as a neutron is basically just that, a proton + an electron,I remember our teacher telling us that P+E=N.How do the quarks change? TL:DR 2 protons collide, but the weak force is here to make our lives harder so it makes a neutrino and a positron (with the latter being the antimatter counterpart of the electron)they’re then carried off by hydrogen isotopes to make helium.

Idk coz my astronomy classes were long ago, like,10 years yo.