Elementary particle the fact that multiple bosons can occupy the same quantum state (Pauli exclusion principle). Also, bosons can be either elementary, like photons, or a combination, like mesons. The spin of bosons are integers instead of half integers. Gluons mediate the strong interaction, which join quarks and thereby form hadrons, which are either baryons (three quarks) or mesons (one quark and one antiquark). Protons and neutrons are baryons, joined by gluons to form the atomic nucleus. Like quarks, gluons exhibit color and anticolor—unrelated to the concept of visual color—sometimes in combinations, altogether eight variations of gluons. There are three weak gauge
Gauge theory are included in the Lagrangian to ensure its invariance under the local group transformations (called "gauge invariance"). When such a theory is quantized, the quanta of the gauge fields are called "gauge bosons". If the symmetry group is non-commutative, then the gauge theory is referred to as non-abelian gauge theory, the usual example being the Yang–Mills theory. Many powerful theories in physics are described by Lagrangians that are invariant under some symmetry transformation groups. When they are invariant under a transformation identically performed at "every" point in the spacetime in which the physical processes occur, they are said to have