The ALICE (A Large Ion Collider Experiment) experiment will study Pb-Pb collisions at the Large Hadron Collider (LHC) until the center of mass energy per nucleon pair √sNN = 5.5 TeV, the highest ever reached. The main physics goal of the experiment is the creation and the investigation of the properties of the strongly-interacting matter in the conditions of high energy density (> 10 GeV/fm3) and high temperatures (~ 0.2 GeV), expected to characterize the medium formed in central heavy-ion collisions at these energies. Under these conditions, according to lattice Quantum Chromo Dynamics (QCD) calculations, quark confinement into colorless hadrons should fade and a deconfined Quark-Gluon Plasma (QGP) should be formed. In the past two decades, experiments at CERN-SPS (√sNN = 17.3 GeV) and BNL-RHIC (√sNN = 200 GeV) have gathered ample evidences for the formation of this state of matter. ALICE, therefore, thanks to the energies available now and in the next future, will open a door in a whole and completely unexplored new regime for the physics of the strong interactions.
In PbPb collisions, resonances can contribute to several topics: first of all, they allow one to probe the collective properties of the interaction fireball, and in particular to estimate its lifetime. Strange resonances with long lifetime, like the phi, can contribute to the historical topic of strangeness production measurement, which is expected to be enhanced as a consequence of QGP formation.
ALICE has also developed a detailed proton-proton physics programme, in order to exploit its capabilities to investigate the novel energy regime made available by LHC, which turns out to be quite interesting in itself besides being important as a baseline for the heavy-ion data.
The study of resonances production in pp contributes to a proper tuning of the QCDinspired particle production models and for a complete understanding of the underlying event.
