Gauge boson more complicated group "SU"(3) has eight generators, corresponding to the eight gluons. The three W and Z bosons correspond (roughly) to the three generators of "SU"(2) in GWS theory. For technical reasons involving gauge invariance, gauge bosons are described mathematically by field equations for massless particles. Therefore, at a naïve theoretical level, all gauge bosons are required to be massless, and the forces that they describe are required to be long-ranged. The conflict between this idea and experimental evidence that the weak and strong interactions have a very short range requires further theoretical insight. According to the Standard Model, the
W′ and Z′ bosons W′ and Z′ bosons In particle physics, W′ and Z′ bosons (or W-prime and Z-prime bosons) refer to hypothetical gauge bosons that arise from extensions of the electroweak symmetry of the Standard Model. They are named in analogy with the Standard Model W and Z bosons. W′ bosons often arise in models with an extra SU(2) gauge group. is spontaneously broken to the diagonal subgroup SU(2) which corresponds to the electroweak SU(2). More generally, we might have "n" copies of SU(2), which are then broken down to a diagonal SU(2). This gives rise to "n"−1 W′, W′ and Z′ bosons.