See the Math Inverse Beta Decay Reaction
Inverse beta decay is a decay mode for radioactive nuclei. It takes place when a proton (p) in the nucleus of an atom interacts with a neutrino (
) to produce a neutron (n) and a positron 
. This is an example of a weak interaction—meaning that the weak nuclear force is acting on these particles—which proceeds via the exchange of a W+ boson.