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

Helium is created through nuclear fusion, which is the process of combining two atomic nuclei to form a heavier nucleus. During fusion, the protons and neutrons in the two nuclei come together to form a single, larger nucleus. The neutron is created when two protons combine, with one proton undergoing beta decay to become a neutron. Beta decay is a type of radioactive decay in which a nucleus emits an electron or positron, and a neutrino or antineutrino. The proton and the electron or positron that is emitted during beta decay combine to form a neutron, which becomes part of the helium nucleus that is created through nuclear fusion.