Particle physics - Liberating quarks and gluons

An extraordinary new state of matter, the quark-gluon plasma, may have been produced. In collisions between high-energy heavy nuclei, temperatures of 1012 K or more are achieved, roughly ten thousand times that in the solar core. Theorists predict that under these conditions there is a drastic change in the structure of nuclear matter. The usual description in terms of baryons (such as protons and neutrons) and mesons (such as pions) must be abandoned in favour of the truly fundamental particles, quarks and gluons. Experiments have now provided the first substantial evidence that such a change occurs.