J[psi] dissociation by light mesons : a journey around the chiral circle

In this thesis, the implication of chiral symmetry implementation for the pion-induced dissociation of the J/psi is examined. A brief introduction of the quark-gluon plasma (QGP) and relativistic heavy ion collisions is first presented followed by a discussion on charmonium modification in nuclear matter. For the latter, a particular emphasis is put on describing the various models used to evaluate the J/psi-dissociation by a meson gas. The consequence of chiral symmetry on the dissociation cross-section by a pion is then explicated. In particular, it is shown that the low-energy dynamics of pions is constrained by the symmetry and that this property is lacking in most present models found in the literature. The derived soft-pion theorem is then integrated into a simple Lagrangian model. The relative importance of the symmetry effect is then assessed in a more comprehensive Lagrangian model and in a model using a constituent quark-based approach