Weak interaction
Beta decay is what scientists call a neutron breaking down, in contrast with alpha decay where an atom breaks down. These types of breaking down are more commonly known as radioactive decay. In a beta decay a neutron breaks into a proton,  an electron and a neutrino. However, this is not a complete picture, there is an intermediary step. Notice that this process preserves the total charge. Conservation laws are very important when calculating the possible outcomes of these interactions.