Quarkonium Production at High-Energy Hadron Colliders

This thesis can be divided into several parts. The first one consists in a detailed historical review of quarkonium physics, centered on the different production models successively introduced. Then comes a review of the currently available data on high-energy hadronic production of J/psi, psi' and Upsilon's. In a third part, we concentrate on the extension of the Colour-Singlet Model beyond the static approximation. In this extension, we emphasise that a simple generalisation of the static case is not sufficient and new 4-point vertices are to be introduced to restore gauge invariance. Since these new vertices are not fully constrained, we propose a method to study this freedom. Finally, we apply our approach to the production at the Tevatron and RHIC, where we show that a combination of our contributions with fragmentation within the Colour-Octet Mechanism is able to reproduce the measurements both for cross sections and for polarisation.