Quark model

Lower valence quarks (or constituent quarks ) is the quarks that determine the important properties of a hadron such as mass, momentum, electric charge and spin. When the proton are a down and two up quarks. The appointment shall be made in accordance with the valence electrons of atomic physics, which are responsible for the chemical properties of atoms essentially.

However, this is only a simplified approximation since interact according to the theory of the strong interaction ( quantum chromodynamics, QCD) quarks in the hadron also with virtual quark-antiquark pairs ( sea quarks ) and virtual gluons that arise in QCD constantly apart. These components from the " quark-gluon sea" contribute to not only the valence mass, momentum and spin of the hadrons.

This leads among other things to a Konstituentenquarkmasse, which is significantly increased compared with the mass of the current quarks that behave in the limit of high energies, such as free particles: for example, in the light up and down quarks to values ​​of about 300 MeV / c ² instead of a few MeV / c ². For total spin the valence quarks carry, for example, the case of protons only about 50% at while 30-50 % are in the beam energy ( values ​​still unsecured). This leads to high center of mass energies.

• Elementary