Heavy Ion Physics at the LHC

<P>Proposal of abstract for HEP99, Tampere, Finland, 15-21 July 1999<P>The Large Hadron Collider (LHC) under construction at CERN is also planned as a heavy ion collider with lead ions colliding at an energy of 5.5 TeV. This corresponds to collisions of matter with cosmic rays of the highest energies observed so far promising the study of new and exciting aspects of physics. In addition to the heaviest system (Pb--Pb), collisions of lower mass ions are foreseen as a means to study collisions at different energy density and proton-nucleus (p--A) collisions provide indispensable reference data for the A--A collisions.<P>ALICE (A Large Ion Collider Experiment) is the only detector fully dedicated to the physics of nuclear collisions. It is designed to cover the full richness of hadronic and leptonic signals expected at the LHC allowing to establish and to study the phase transition from hadronic matter to deconfined partonic matter, the quark gluon plasma (QGP). <P>The CMS experiment is optimised for the study of hard processes in high luminosity pp collisions at the LHC. It has a large muon detection and calorimetric coverage of the central rapidity region. The collaboration expressed its intention to exploit these capabilities to study high mass muon pairs and large transverse energy jets in heavy ion collisions.