3.5.5 Quantum Chromodynamics
Dirac attempts to quantize the electromagnetic field, by constructing a quantum theory starting from the classical electromagnetism, became a model to build quantum field theories for other interactions, such as the Quantum Chromodynamics (QCD) of the strong interaction between quarks and gluons.
In 1933, Enrico Fermi established that the creation, annihilation and transmutation of particles in the weak interaction beta decay could best be described in Quantum Field Theory. As a result, field theory had become a prospective tool for other particle interactions. Quantum Electrodynamics, as described in section 5.3, served as the model for all subsequent quantum field theories, such as Quantum Chromodynamics (QCD), which began in the early 1960s. QCD is the theory of the strong interaction between quarks and gluons, the fundamental particles that make up composite hadrons such as the proton, neutron and pion. QCD theory is an important part of the Standard Model of particle physics, to be described in section 5.18.