  Since a long-time, the quantum integrable systems have remained an area where
modern mathematical methods have given an access to interesting results in the
study of physical systems. The exact computations, both numerical and
asymptotic, of the correlation function is one of the most important subject of
the theory of the quantum integrable models. In this context an approach based
on the calculation of form factors has been proved to be a more effective one.
In this thesis, we develop a new method based on the algebraic Bethe ansatz for
the computation of the form-factors in thermodynamic limit. It is both applied
to and described in the context of isotropic XXX Heisenberg chain, which is one
of the examples of an interesting case of critical models where the Fermi-zone
is non-compact. In a particular case of two-spinon form-factors, we obtain an
exact result in a closed-form which matches the previous result obtained from
an approach based on $q$-vertex operator algebra. This method is then
generalised to form-factors in higher spinon sectors where we find a reduced
determinant representation for the form-factors, in which a higher-level
structure for the form-factors is revealed.
