For example, we have a very successful theory of the strong nuclear forces, called quantum chromodynamics [QCD], which is based on the idea that quarks are bound together by forces that increase with distance, so that we will never, even in principle, be able to observe a quark in isolation. (scientificamerican.com)
«Finding a doubly heavy quark baryon is of great interest, as it will provide a unique tool to further probe quantum chromodynamics [QCD]-- the theory that describes the strong [force], one of the four fundamental forces,» LHCb spokesperson Giovanni Passaleva said in a statement. (scientificamerican.com)
(Quarks come in three «colors,» analogous to electric charge; hence the «chromo» in chromodynamics.) (discovermagazine.com)