2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/195876The physics of gluon saturation and non-linear evolution at small values of parton momentum fraction x in the proton and nucleus is discussed in the context of experimental results at HERA and RHIC. The rich physics potential of low-x QCD studies at the LHC is discussed and some measurements in pp, pA and AA collisions accessible with the Compact Muon Solenoid (CMS) experiment are presented.Extended clarifications to Eq. (6). A couple of typos corrected. To appear in EPJCHigh Energy Physics - ExperimentNuclear Experimenttext