Identical particles fermions, which do not share quantum states as described by the Pauli exclusion principle. Examples of bosons are photons, gluons, phonons, helium-4 nuclei and all mesons. Examples of fermions are electrons, neutrinos, quarks, protons, neutrons, and helium-3 nuclei. The fact that particles can be identical has important consequences in statistical mechanics. Calculations in statistical mechanics rely on probabilistic arguments, which are sensitive to whether or not the objects being studied are identical. As a result, identical particles exhibit markedly different statistical behaviour from distinguishable particles. For example, the indistinguishability of particles has been proposed as a solution to Gibbs' mixing
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.