2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/40035Lattice quantum chromodynamics (QCD) predicts a new state of matter, called quark-gluon plasma (QGP), at sufficiently high temperatures or equivalently large energy densities. Relativistic heavy ion collisions are expected to produce such energy densities, thereby providing us a chance to test the above prediction. After a brief introduction of the necessary theoretical concepts, I present some critical comments on the experimental results with an aim to examine whether QGP has already been observed experimentally.Plenary Talk given at IVth Rencontres du Vietnam, Hanoi, July 2000; LaTeX, 8 pages including 3 eps figures, uses moriond.styHigh Energy Physics - Phenomenologytext