Leptogenesis in smooth hybrid inflation

We present a concrete supersymmetric grand unified model based on the Pati- Salam gauge group SU(4)(c) x SU(2)(L) x SU(2)(R) and leading naturally to s mooth hybrid inflation, which avoids the cosmological disaster encountered in the standard hybrid inflationary scenario from the overproduction of mon opoles at the end of inflation. Successful 'reheating' which satisfies the gravitino constraint takes place after the termination of inflation. Also, adequate baryogenesis via a primordial leptogenesis occurs consistently wit h the solar and atmospheric neutrino oscillation data as well as the SU(4)( c) symmetry. (C) 2001 Elsevier Science B.V. All rights reserved.