What statistics do integer-spin particles obey?

Integer-spin particles obey Bose–Einstein statistics.

Particles with integer values of spin, including spin 0, 1, or 2, are called bosons. Bose–Einstein statistics describe how identical bosons can occupy the same quantum state in unlimited numbers. This behavior contrasts with fermions, which have half-integer spin and obey Fermi–Dirac statistics.

The statistical theory grew from work by Satyendra Nath Bose and Albert Einstein in the 1920s. Bose developed the counting method for photons, and Einstein extended it to material particles. Their work predicted Bose–Einstein condensation, a state in which many bosons occupy the same lowest-energy state and behave collectively.

Familiar bosons include photons, gluons, and the W and Z bosons. Composite particles can also be bosons when their total spin is integer; helium-4 atoms are a well-known example. The spin-statistics connection is a result of relativistic quantum field theory, not merely a classification based on a particle’s name.

A common mix-up is treating “quantum statistics” as a competing answer. Quantum statistics is the broad category containing both Bose–Einstein and Fermi–Dirac statistics. Maxwell–Boltzmann statistics instead approximate dilute classical gases when quantum effects are negligible.