In particle physics, a boson is a particle that follows Bose–Einstein statistics. Bosons make up one of the two classes of elementary particles, the other being fermions. The name boson was coined by Paul Dirac after Satyendra Nath Bose and Albert Einstein who worked on developing statistical mechanics to explain why some particles follow these statistics.
Bosons are distinguished from fermions, which obey Fermi–Dirac statistics. Both bosons and fermions can be either elementary particles—that is, not composed of any other known particles—or composite particles, like atoms and molecules. If a composite particle contains an even number of fermions (quarks or electrons), it will be a boson; if it contains an odd number of fermions, then it will be a fermion; see Pauli exclusion principle for more details.
All known force-carrying particles—gauge bosons—are bosons (with the exception of the Higgs boson). The Standard Model includes the photons of electromagnetism and the W± and Z0 vector bosons of the weak interaction (weak nuclear force). Composite spin-1 gauge bosons include mesons in quantum chromodynamics (strong nuclear force). Spin-2 gravitons are also thought to be elementarybosons according to current theories such as quantum gravity and string theory.