## Quick Reference

A spin-one vector boson that mediates interactions governed by gauge theories. Examples of gauge bosons are photons in quantum electrodynamics, gluons in quantum chromodynamics, and W and Z bosons that mediate the interactions in the Weinberg–Salam model (see electroweak theory) unifying electromagnetic and weak interactions. If the gauge symmetry of the theory is unbroken, the gauge boson is massless. Examples of massless gauge bosons include the photon and gluon. If the gauge symmetry of the theory is a broken symmetry, the gauge boson has a nonzero mass, examples being the W and Z bosons. Treating gravity, as described by the general theory of relativity, as a gauge theory, the gauge boson is the massless spin-two graviton.

**From:**
gauge boson
in
A Dictionary of Physics »

*Subjects:*
Physics.