In hadrons such as [[proton]]s and [[neutron]]s the rest mass of the constituent [[quark]]s only account for a tiny fraction of the total mass of the particle. The remainder is the mass-equivalent of the kinetic energy of the quarks and [[gluon]]s which bind them as they move confined within the particle. | In hadrons such as [[proton]]s and [[neutron]]s the rest mass of the constituent [[quark]]s only account for a tiny fraction of the total mass of the particle. The remainder is the mass-equivalent of the kinetic energy of the quarks and [[gluon]]s which bind them as they move confined within the particle. |