Inflation and monopoles in supersymmetric SU(4)c × SU(2)L × SU(2)R

We show how hybrid inflation can be successfully realized in a supersymmetricmodel with gauge group G_{PS}= SU(4)_c x SU(2)_L x SU(2)_R. By including anon-renormalizable superpotential term, we generate an inflationary valleyalong which G_{PS} is broken to the standard model gauge group. Thus,catastrophic production of the doubly charged magnetic monopoles, which arepredicted by the model, cannot occur at the end of inflation. The results ofthe cosmic background explorer can be reproduced with natural values (of order10^{-3}) of the relevant coupling constant, and symmetry breaking scale ofG_{PS} close to 10^{16} GeV. The spectral index of density perturbations liesbetween unity and 0.9. Moreover, the mu-term is generated via a Peccei-Quinnsymmetry and proton is practically stable. Baryogenesis in the universe takesplace via leptogenesis. The low deuterium abundance constraint on the baryonasymmetry, the gravitino limit on the reheat temperature and the requirement ofalmost maximal mu neutrino - tau neutrino mixing from SuperKamiokande can besimultaneously met with mu-neutrino, tau-neutrino and heaviest Dirac neutrinomasses determined from the large angle MSW resolution of the solar neutrinoproblem, the SuperKamiokande results and SU(4)_c symmetry respectively.Comment: 29 pages including 7 figures, Latex, version published in JHE