Contribution to the study of elementary particles in experiments involving accelerators

This document reviews the theoretical, experimental and technical achievements of the author since the beginning of his scientific career. Works in 5 fields have been highlighted: 1) rare decays of the η meson, 2) neutrino oscillations in NOMAD experiment, 3) quark and gluon plasma, 4) the PHENIX experiment at RHIC, and 5) the ALICE experiment in LHC. The PHENIX experiment was dedicated to the accurate measuring of photons and dileptons (particularly J/Ψ, Ψ' resonances) produced in heavy ion collisions. The ALICE experiment is devoted to the study of the quark gluon plasma. Its detector must be able to detect charged particles with a broad range of transverse momenta (from 100 MeV/c to 100 GeV/c). This document presented before an academic board will allow his author to manage research works and particularly to tutor thesis students