We don't have synonyms for z boson yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are w boson, x boson and z-boson.
(n) :
Alternative form of Z-boson. [(particle physics) a fundamental particle, a gauge boson, that, together with the W-boson, mediates the weak nuclear force; it has a charge of 0]
(n) :
Alternative form of Z-boson. [(particle physics) a fundamental particle, a gauge boson, that, together with the W-boson, mediates the weak nuclear force; it has a charge of 0]