Bosön - Properties of Bosons

Properties of Bosons

Bosons contrast with fermions, which obey Fermi–Dirac statistics. Two or more fermions cannot occupy the same quantum state (see Pauli exclusion principle).

Since bosons with the same energy can occupy the same place in space, bosons are often force carrier particles. In contrast, fermions are usually associated with matter (although in quantum physics the distinction between the two concepts is not clear cut).

Bosons may be either elementary, like photons, or composite, like mesons.

All observed bosons have integer spin, as opposed to fermions, which have half-integer spin. This is in accordance with the spin-statistics theorem, which states that in any reasonable relativistic quantum field theory, particles with integer spin are bosons, while particles with half-integer spin are fermions.

While most bosons are composite particles, in the Standard Model, there are five bosons which are elementary:

• the four gauge bosons (γ · g · Z · W±)
• the Higgs boson (H0).

Additionally, the graviton (G), a hypothetical elementary particle not incorporated in the Standard Model, if it exists, must be a boson, and could conceivably be a gauge boson.

Composite bosons are important in superfluidity and other applications of Bose–Einstein condensates.