Graduate thesis
**Title **

Two
aspects of strong interactions

**Abstract**

In Part I, I shall present some aspects of the production of
heavy quarkonia in hadronic collisions. This is the direct continuation
of
my
undergraduate dissertation .
More precisely, I shall consider the uncertainties specific to
the theoretical model used, * i.e. * the Color Singlet Model. I
shall give an analysis of the influence of the uncertainties of the
proton parton distribution functions on the differential cross-sections
of hadronic heavy quarkonia production as well as the influence of the
uncertainties on the wave function. The point of this study is to show
-- even if this was commonly believed -- that theoretical errors are
not sufficient to explain the discrepancies between Tevatron
measurements and the predictions of the CSM as exposed in the Chapter 2
of
my undergraduate dissertation . This study moreover allowed me to
quantify the theoretical errors with a better precision.
Still in Part I, I shall then expose my work on the introduction of a
non-vanishing relative three-momentum between quarks constituting the
heavy mesons. Another step in the improvement of the classical CSM
which I shall mention is the introduction of a non-vanishing relative
energy and of a relativistic wave function for the mesons. In the
following, I shall talk about * the non static extension of the CSM *
when refering to this improvement.
Part II will be devoted to the study of pion and scalar
structure functions. The study of these is part of a wider project
related to off-diagonal hadron structure functions and is done in
context of the
ESOP European Network.
The subjects of Part I and Part II, although a priori not linked, do
not differ substantially. As it will appear, the structure of the
calculations of quarkonia production and of our model for pion
structure functions are somehow
very similar. In a general point of view, the main differences come
from the
nature of the particules which induce different vertex functions and
differences
in kinematics.

**Postscript
version (gzipped) **