Boson

A boson is a type of particle that has an integer spin (0, 1, 2, …). Bosons obey Bose-Einstein statistics, which allow multiple identical bosons to occupy the same quantum state. This contrasts with fermions, which have half-integer spin and obey Fermi-Dirac statistics, enforcing the Pauli exclusion principle.

Bosons can be elementary or composite. Elementary examples include gauge bosons that mediate fundamental forces—photons for electromagnetism, gluons for the strong force, and the W and Z bosons for the weak force. The Higgs boson is a scalar boson associated with the Higgs field. Many composite particles, such as mesons (quark-antiquark pairs), are also bosons because their total spin is an integer. Because of their integer spin, bosons can occupy the same quantum state, enabling phenomena like coherence and macroscopic occupation of a single state.

In quantum field theory, bosons are understood as quanta of fields. Force interactions are described as the exchange of bosons between other particles, with gauge bosons acting as force carriers. The Higgs boson is associated with the mechanism that endows certain particles with mass.

History and terminology: the concept arises from Satyendra Nath Bose’s work on photon statistics, which Einstein extended to matter waves. The term “boson” was later coined, in reference to Bose, to denote particles obeying Bose-Einstein statistics.

Bose-Einstein condensation is a notable phenomenon where, at very low temperatures, a large fraction of bosons occupy the lowest quantum state, leading to macroscopic quantum effects.