Quantum chromodynamics binding energy
Quantum chromodynamics binding energy, gluon binding energy or chromodynamic binding energy is the energy binding quarks together into hadrons. It is the energy of the field of the strong force, which is mediated by gluons. Motion-energy and interaction-energy contribute most of the hadron's mass.
Gluon energy
While gluons are massless, they still possess energy — chromodynamic binding energy. In this way, they are similar to photons, which are also massless particles carrying energy — photon energy. The amount of energy per single gluon, or "gluon energy", cannot be directly measured, though a distribution can by inferred from deep inelastic scattering experiments Unlike photon energy, which is quantifiable, described by the Planck–Einstein relation and depends on a single variable, no simple formula exists for the quantity of energy carried by each gluon. While the effects of a single photon can be observed, single gluons have not been observed outside of a hadron. A hadron is in totality composed of gluons, valence quarks, sea quarks and other virtual particles.The gluon content of a hadron can be inferred from DIS measurements. Again, not all of the QCD binding energy is gluon interaction energy, but rather, some of it comes from the kinetic energy of the hadron's constituents. Currently, the total QCD binding energy per hadron can be estimated through a combination of the factors mentioned. In the future, studies into quark–gluon plasma will better complement the DIS studies and improve our understanding of the situation.