Analyse des données des calorimètres d’ALICE et étude de la production des hadrons de basse impulsion dans les collisions de grande énergie

The ALICE experiment at LHC is dedicated to the study of many facets of the strong interaction. The microscopic theory of the latter, QCD, and its manifestation in particle production can be thoroughly explored by studying jet observables. Central to the study of jet physics with ALICE is the mastering of its calorimetry. This is one of the topics addressed in this work namely carrying out one of the first tasks which is to verify thequality of available data. For this purpose the Quality Assurance (QA) framework for ALICE electromagnetic calorimeters, PHOS and EMCAL, was developed. On this base,the measurement of neutral pions,$\pi^0$ and $\eta$, via their two photon decays was performed. The success in understanding dynamics of soft particles inside jets relies on calculations of perturbative QCD, impressive accuracy of which has already been tested experimentally.The theory predicts that the inclusive particle spectrum inside jets is independent of a collision energy in the limiting case of zero momentum ($p\rightarrow0$). In order to test this prediction, a systematic study of world experimental data from hadron and lepton colliders at the collision energies from tens of GeV up to the TeV scale at the LHC has been performed.