nuclearforce

The nuclear force, commonly called the strong nuclear force or strong interaction, is the fundamental interaction that binds protons and neutrons (nucleons) within atomic nuclei. It is the strongest of the four fundamental forces at subatomic distances, but it is short-ranged, operating effectively only over distances on the order of 1 femtometer (10^-15 meters).

In the framework of quantum chromodynamics (QCD), the strong interaction between quarks is mediated by gluons and exhibits properties such as asymptotic freedom and confinement. Protons and neutrons themselves are color-neutral composites of quarks, and the nuclear force between them is a residual effect of their quark-gluon interactions. Traditionally, the residual strong force between nucleons is described by meson exchange, notably pions, yielding an attractive potential at intermediate ranges and a repulsive core at very short distances that prevents collapse.

The nuclear force is responsible for binding energy in nuclei, determining nuclear stability and the limits of nuclear existence. It saturates: each nucleon interacts strongly with only a few nearest neighbors, leading to the characteristic patterns of nuclear binding and shell structure. While the electromagnetic repulsion between protons is a competing factor, the net effect of the nuclear force keeps most atomic nuclei bound.