Why are there eight gluons and not nine? According to QCD and the standard model of particle physics, quarks carry an SU(3) "color charge" which can be "red", "blue" or "green". The strong nuclear force which binds these together inside the nucleons is mediated by gluons which must carry a color-anticolor charge.
Higgs boson (this one hasn’t been found yet) In addition, many physicists believe that there probably exists a boson called the graviton, which is related to gravity. Composite bosons can also exist; these are formed by combining together an even number of different fermions.
W + or W − boson either raises or lowers the electric charge of the emitting particle by one unit, and also alters the spin by one unit. At the same time, the emission or absorption of a W boson can change the type of the particle – for example changing a strange quark into an up quark.
As the Z boson is a mixture of the pre-symmetry-breaking W 0 and B 0 bosons (see weak mixing angle), each vertex factor includes a factor T 3 − Q sin 2 θ W; where T 3 is the third component of the weak isospin of the fermion, Q is the electric charge of the fermion (in units of the elementary charge), and θ W is the weak mixing angle.