Quarkonium Production at High-Energy Hadron Colliders

TL;DR

This thesis reviews quarkonium production models, analyzes experimental data, extends the Colour-Singlet Model beyond static approximation, and demonstrates improved agreement with collider measurements by combining this with the Colour-Octet Mechanism.

Contribution

It introduces a novel extension of the Colour-Singlet Model with new vertices to restore gauge invariance and combines it with the Colour-Octet Mechanism for better data agreement.

Findings

Extended model reproduces cross sections at Tevatron and RHIC.

New vertices restore gauge invariance in the extended model.

Combination with the Colour-Octet Mechanism explains polarization data.

Abstract

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.