Constituent quark

A constituent quark is a current quark with a covering.

In the low energy limit of QCD, a description by means of perturbation theory is not possible. Here, no Asymptotic freedom exists, but the interactions between valence quarks and sea-quarks gain strongly on significance. Part of the effects of virtual quarks and virtual gluons in the 'sea' can be assigned in each case to a quark, so well that this is the one of the main proofs that the usage of the term constituent quark is just making sense.

Accordingly to the Feynmangraphs, constituent quarks seem to be 'tightened' current quarks, thus, current quarks with constituent quark covering. These coverings are in the long run responsible for the large masses of the constituent quarks.

Definition: Constituent quarks are valence quarks. In those, the correlations for the description of the hadrons guided by gluons and sea-quarks is to be put into effective quark masses of these valence quarks.

The effective quark mass is called also constituent quark mass. Hadrons consist of 'sticking' constituent quarks. The use of the local term for the description of the hadrons used on light constituent quarks is not completely unproblematic.

Local term on constituent quarks:
Particle	Mass	(standard deviation Δx of the position measurements)
constituent quark (up, down)	$m_{(}u,d)$ =300MeV	$\Delta$x =0,7fm

Describing hadrons using nonrelativistic quantum mechanics becomes to be only possible under forced difficult circumstances.