[!lemma=","] □
[!lemma=","] □ □
[!lemma=","] (□ | □)
We choose the initial wave function to describe a condensate , where the N bosons are all in the same one-particle state . Quarks and leptons are assumed to be fundamental objects , and all their interactions are mediated by force carriers called bosons , with the Z boson being the heaviest carrier of the electroweak force . That 's because the Z0 boson is short-lived and decays to certain other particles ; the number of these particles influences the decay process . Now the W boson is also understood to be a fundamental particle in its own right , and it can " couple " at a point in space and time ( called a vertex ) with two other particles whose charges add up to the W charge ( you also have to preserve other things like lepton and baryon number , but we do n't have to go into all of that for this answer ) . The neutrino from this new generation can ’ t really be light because the number of neutrinos lighter than the Z bosons is measured from the decay rate of Z , and the experimental result is 3 + -0.01 or so .