Quantum chromodynamics (QCD) is the study of the strong interaction, a fundamental force that governs the behavior of subatomic particles known as quarks and gluons. The strong interaction is responsible for the binding of protons and neutrons in atomic nuclei, as well as the interactions between hadrons (a class of particles that includes protons and neutrons). QCD is a quantum field theory that describes the strong interaction in terms of these elementary particles.
The name “quantum chromodynamics” was first coined by American physicist Murray Gell-Mann in 1973. The word “chromo” comes from a Greek root meaning “color,” referring to one of the three properties of quarks that determines their interactions: red, green, and blue. (The other two properties are called flavor and spin.) Gluons are also colored particles; they mediate the strong force between quarks.
Quantum chromodynamics is similar to quantum electrodynamics (QED), which describes the electromagnetic force between charged particles such as electrons. Both theories are based on principles of quantum mechanics and special relativity. However, QCD is much more complicated than QED because it must take into account the fact that quarks come in different colors, while electrons do not. This makes it difficult to solve problems using perturbation theory, a common technique in quantum field theory. As a result, most calculations in QCD must be done numerically using computers.
Despite its complexity, quantum chromodynamics has been very successful in explaining a wide range of experimental data. For example, it correctly predicts the masses of hadrons and their interactions with each other. It also explains why some hadrons are stable while others decay quickly into other particle types. In addition, QCD has provided insights into phenomena such as high-energy collisions between nuclei or beams of subatomic particles