Première mesure de l'asymétrie azimutale de la production du $J/\psi$ vers l'avant dans les collisions Au+Au à 200 GeV par paire de nucléons avec l'expérience PHENIX

One of hight energy experiment main goal is the study of nuclear matter under extreme conditions. Ultra- relativistic Au+Au collisions at 200 GeV per binary nucleon-nucleon collision could generate high enough temperature and energy density to form a new state of matter, the quark gluon plasma (QGP), where quarks and gluons would be free from strong interactions. The J/ψ is a heavy particle made of charm quarks (c ̄). The study of its production has been suggested c a QGP probe. J/ψ suppression was initially expected if a QGP was formed because of screening between charm quarks within a dense colored medium. Lots of J/ψ measurements have been made at SPS (CERN) and RHIC (BNL). They have allowed to point out this suppression but also showed the presence of additional mechanisms, which lead to a more difficult interpretation of the results. The PHENIX experiment is the only one of RHIC experiments to be able to measure the J/ψ at positive √ rapidity via its disintegration into two muons. In 2007, RHIC collided Au ions at sN N = 200 GeV in the center of mass, which allowed to increase by a factor four the available statistics for J/ψ studied compared to previous published results. Such statistics, combined with the installation of new detectors in PHENIX, helped to increase previous measurements precision, and to measure new observables such as the azimuthal asymmetry of J/ψ production. This manuscript presents today understanding of quarkonia production, and the use of this probe in QGP study. The analysis that leads to the first measurement of J/ψ azimuthal anisotropy at positive rapidity in Au+Au collisions at 200 GeV per nucleon-nucleon collisions is detailed. This measurement should help understand J/ψ production mechanism, especially concerning the level of c quark recombinaison into J/ψ.