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

We show how hybrid inflation can be successfully realized in a supersymmetr ic model with gauge group G(PS) = SU(4)c x SU(2)(L) x SU(2)(R). By includin g a non-renormalizable superpotential term, we generate an inflationary val ley along which GPS is broken to the standard model gauge group. Thus, cata strophic production of the doubly charged magnetic monopoles, which are pre dicted by the model, cannot occur at the end of inflation. The results of t he cosmic background explorer can be reproduced with natural values (of ord er 10(-3)) of the relevant coupling constant, and symmetry breaking scale o f G(PS) of the order of 10(16) GeV. The spectral index of density perturbat ions lies between unity and 0.9. Moreover, the mu -term is generated via a Peccei-Quinn symmetry and proton is practically stable. Baryogenesis in the universe takes place via leptogenesis. The low deuterium abundance constra int on the baryon asymmetry, the gravitino limit on the reheat temperature and the requirement of almost maximal nu (mu) - nu (tau) mixing from SUPER- KAMIOKANDE can be simultaneously met with m(nu mu), m(nu tau) and heaviest Dirac neutrino mass determined from the large angle MSW resolution of the s olar neutrino problem, the SUPER-KAMIOKANDE results and SU(4)(c) symmetry r espectively.