The W and Z particles interact with the Higgs boson as shown in the Feynman diagram.
[4] The name vector boson arises from quantum field theory.
The component of such a particle's spin along any axis has the three eigenvalues −ħ, 0, and +ħ (where ħ is the reduced Planck constant), meaning that any measurement of its spin can only yield one of these values.
(This is true for massive vector bosons; the situation differs for massless particles such as the photon, for reasons beyond the scope of this article.
[5]) The space of spin states therefore is a discrete degree of freedom consisting of three states, the same as the number of components of a vector in three-dimensional space.