THE standard model of particle physics is a stunning achievement. It offers a concise description of the basic constituents of the universe, the particles and forces that make reality, that agrees with every experimental test we have thrown at it. By most measures, it is the most successful scientific theory ever devised.
But as we explore in our special feature celebrating its 50th anniversary, the standard model remains unfinished. It leaves open several profound questions, from the true nature of dark matter and dark energy to why there is more matter than antimatter in the universe.
Physicists are desperately seeking …