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 Lagrangian. In the quantized version of the obtained classical field theory, the quanta of the gauge field "A"("x") are called gauge bosons. The interpretation of the interaction Lagrangian in quantum field theory is of scalar bosons interacting by the exchange of these gauge bosons. The picture of a classical gauge theory developed in the previous section is almost complete, except for the fact that to define the covariant derivatives "D", one needs to know the value of the gauge field formula_29 at all space-time points. Instead of manually specifying the values of this field, it can be given as the