What is this nuclear reaction an example of: #4 "_1^1H## ->## "_2^4He# + #2 "" _(+1)^0beta#?
A nuclear reaction in which a hwavier nucleus (in this case He-4) is made by combining several lighter ones (the four protons on the left) is called (nuclear) fusion.
Fusion of hydrogen to helium is the energy source for most stars including our Sun. Scientists are exploring hiw to reproduce this reaction, which requires maintaining temperatures of tens of millions of degrees or more. When they succeed the result will be an almost limitless and relatively clean source of energy. See https://en.wikipedia.org/wiki/Nuclear_fusion.