Do the quarks or leptons have any substructure, or are they truly elementary particles?
• Is there really a Higgs boson, as predicted by the Standard Model of particle physics? If so, what is its mass? If not, what breaks the symmetry between the electromagnetic and weak forces, and gives all the elementary particles their masses? The Standard Model predicts the existence of a spin-0 particle called the Higgs boson, which comes in two isospin states, one with charge +1 and one neutral. (It also predicts that this particle has an antiparticle.) According to the Standard Model, the interaction of the Higgs boson with the electroweak force is responsible for a “spontaneous symmetry breaking” process that makes this force act like two very different forces: the electromagnetic force and the weak force. Moreover, it is primarily the interaction of the Higgs boson with the other particles in the Standard Model that endows them with their masses! The Higgs boson is very mysterious, because in addition to doing all these important things, it stands alone, very different from all
