Coleman-Weinberg SO(10) grand unified theories as inflationary models

The flat-space limit of the one-loop effective potential for SO(10) GUT’s in spatially flat Friedmann- Robertson-Walker cosmologies is applied to study the dynamics of the early universe. The numerical integration of the corresponding field equations shows that, for such grand unified theories, a sufficiently long inflationary stage is achieved for suitable choices of the initial conditions. However, a severe fine-tuning of these initial conditions is necessary to obtain a large e-fold number. In the direction with residual symmetry SU(4)PS SU(2)L SU(2)R, one eventually finds parametric resonance for suitable choices of the free parameters of the classical potential. This phenomenon leads in turn to the end of inflation