Strong interaction

In nuclear physics and particle physics, the strong interaction, also called the strong force or strong nuclear force, is a fundamental interaction that confines quarks into protons, neutrons, and other hadron particles. The strong interaction also binds neutrons and protons to create atomic nuclei, where it is called the nuclear force.

Most of the mass of a proton or neutron is the result of the strong interaction energy; the individual quarks provide only about 1% of the mass of a proton. At the range of 10⁻¹⁵ m (1 femtometer, slightly more than the radius of a nucleon), the strong force is approximately 100 times as strong as electromagnetism, 10⁶ times as strong as the weak interaction, and 10³⁸ times as strong as gravitation.^[1]

In the context of atomic nuclei, the force binds protons and neutrons together to form a nucleus and is called the nuclear force (or residual strong force).^[2] Because the force is mediated by massive, short lived mesons on this scale, the residual strong interaction obeys a distance-dependent behavior between nucleons that is quite different from when it is acting to bind quarks within hadrons. There are also differences in the binding energies of the nuclear force with regard to nuclear fusion versus nuclear fission. Nuclear fusion accounts for most energy production in the Sun and other stars. Nuclear fission allows for decay of radioactive elements and isotopes, although it is often mediated by the weak interaction. Artificially, the energy associated with the nuclear force is partially released in nuclear power and nuclear weapons, both in uranium or plutonium-based fission weapons and in fusion weapons like the hydrogen bomb.^[3][4]