Search

One of the major objectives of this dissertation has been the seek for inflationary models, coming from supersymmetric theories, which are compatible with recent cosmological data and, more specifically, with measurements of the spectral index from the WMAP3 data. A particular particle physics model, the extended SUSY Pati-Salam model with Yukawa quasi-unification, was examined thoroughly with respect to its cosmology and it was found that it incorporates a number of inflationary scenarios which can become compatible with recent data. The study of these scenarios brought out variations of cosmological models which might be important in cosmological research., Comment: 99 pages including 11 figures

We discuss a new inflationary scenario which is realized within the extended supersymmetric Pati-Salam model which yields an acceptable b-quark mass for universal boundary conditions and mu>0 by modestly violating Yukawa unification and leads to new shifted, new smooth, or standard-smooth hybrid inflation. Inflation takes place along a "semi-shifted" classically flat direction on which the U(1)_{B-L} gauge group remains unbroken. After the end of inflation, U(1)_{B-L} breaks spontaneously and a network of local cosmic strings, which contribute a small amount to the curvature perturbation, is produced. We show that, in minimal supergravity, this "semi-shifted" inflationary scenario is compatible with a recent fit to data which uses field-theory simulations of a local string network. Taking into account the requirement of gauge unification, we find that, for spectral index n_s=1, the predicted fractional contribution f_{10} of strings to the temperature power spectrum at multipole l=10 is about 0.039. Also, for f_{10}=0.10, which is the best-fit value, we obtain that n_s is about 1.0254. Spectral indices lower than about 0.98 are excluded and blue spectra are slightly favored. Magnetic monopoles are not formed at the end of semi-shifted hybrid inflation., Comment: 11 pages including 3 figures, uses Revtex, version to appear in Phys. Rev. D