Limits on SUSY GUTs and Defects Formation in Hybrid Inflationary Models with Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations

We confront the predicted effects of hybrid inflationary models on the Cosmic Microwave Background (CMB) with three years of Wilkinson Microwave Anisotropy Probe (WMAP) observations. Using model selection, we compare the ability of a simple flat power-law LCDM model to describe the data to hybrid inflationary models involving global or local cosmic strings, or global textures. We find that it is statistically impossible to distinguish between these models: they all give a similar description of the data, the maximum ratio of the various evidences involved being never higher than e^{0.1 \pm 0.5}. We then derive the maximum contribution that topological defects can make to the CMB, and place an upper bound on the possible value of cosmic strings tension of G\mu \leq 2.1 \times 10^{-7} (68% CL). Finally, we give the corresponding constraints on the strings and D-strings masses, as well as limits on the D- and F-term coupling constants (\kappa and \lambda) and mass scales (M and \sqrt{\xi})