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Université Claude Bernard - Lyon I (09/11/2011), Guy Chanfray et Kawtar Hafidi (Dir.)
Fragmentation des Quarks et Formation des Hadrons dans la Matière Nucléaire
Raphaël Dupré1

The hadron formation is, in the framework of the quantum chromodynamics theory (QCD), a non-perturbative process; this characteristic leads to important theoretical challenges. This is why experimental measurements of fragmentation in nuclei are a necessity in order to obtain substantial progress in our understanding of the mechanisms of hadron formation. The thesis begins with the introduction of theoretical background, followed by an overview of theoretical models. The thesis continues with the analysis of Jefferson Lab data obtained with a 5 GeV electron beam incident on various targets ($^2$H, C, Al, Fe, Sn and Pb).The reaction products are measured with the CLAS spectrometer of Hall B. The main results are: (a) multi-dimensional analysis of the measured observables, which permits a better confrontation with theoretical models and the extraction of temporal information on fragmentation, and (b) the observation of a non linear hadronic attenuation as a function of the target's nuclear radius. The PyQM event generator, developed to reproduce the data from the HERMES collaboration, is also presented. The results are ambivalent, the theoretical basis used does not seem to apply to the studied case, however, some characteristics of the data are reproduced allowing to understand their origin, which is sometimes unexpected. Finally, the possibilities for future experiments, at Jefferson Lab and at an Electron-Ion Collider (EIC), are explored.
1 :  IPNL - Institut de Physique Nucléaire de Lyon
Physique/Physique Nucléaire Expérimentale
Fragmentation – hadronisation – QCD – Jefferson Lab – CLAS – noyau – Monte-Carlo – perte d'énergie des quarks – collisionneur électron-ion – EIC
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