  In the framework of Supersymmetric Grand Unified Theories (SUSY GUTs), the
universe undergoes a cascade of symmetry breakings, during which topological
defects can be formed. We address the question of the probability of cosmic
string formation after a phase of hybrid inflation within a large number of
models of SUSY GUTs in agreement with particle and cosmological data. We show
that cosmic strings are extremely generic and should be used to relate
cosmology and high energy physics. This conclusion is employed together with
the WMAP CMB data to strongly constrain SUSY hybrid inflation models. F-term
and D-term inflation are studied in the SUSY and minimal SUGRA framework. They
are both found to agree with data but suffer from fine tuning of their
superpotential coupling (\lambda \lesssim 3\times 10^(-5) or less). Mass scales
of inflation are also constrained to be less than M \lesssim 3\times 10^(15)
GeV.
