Quark–gluon plasma in their Nature PR. Quark–gluon plasma is a state of matter in which the elementary particles that make up the hadrons of baryonic matter are freed of their strong attraction for one another under extremely high energy densities. These particles are the quarks and gluons that compose baryonic matter. In normal matter quarks are "confined"; in the QGP quarks are "deconfined". In classical QCD quarks are the fermionic components of hadrons (mesons and baryons) while the gluons are considered the bosonic components of such particles. The gluons are the force carriers, or bosons, of the QCD color force, while the
Chirality (physics) to begin with, and therefore the pions are not massless, but have small masses: they are pseudo-Goldstone bosons. For more "light" quark species, flavors in general, the corresponding chiral symmetries are "U(N)×U(N)", decomposing into and exhibiting a very analogous chiral symmetry breaking pattern. Most usually, = 3 is taken, the "u, d", and "s" quarks taken to be light (the Eightfold way (physics)), so then approximately massless for the symmetry to be meaningful to a lowest order, while the other three quarks are sufficiently heavy to barely have a residual chiral symmetry be visible for practical purposes. In theoretical physics,