Induced gravity inflation in the SU(5) GUT

Abstract

We investigate the cosmological consequences of a theory of induced gravity in which the scalar field is identified with the Higgs field of the first symmetry breaking of a mi\-ni\-mal SU(5) GUT. The mass of the X-boson determines a great value for the coupling constant of gravity-particle physics. Because of this fact, a "slow" rollover dynamics for the Higgs field is not possible in a "new" inflation scenario and, moreover, a contraction era for the scale factor in the early universe exists, \-after\- which inflation follows automatically; "chaotic" inflation is performed without problems. Inflation is successfully achieved due to the relationship among the masses of particle physics at that scale: The Higgs-, X-boson- and Planck-masses. As a result the particle physics pa\-ra\-me\-ter $\lambda$ is not fine-tuned as usual in order to predict acceptable values of re-heating temperature and density and gravitational wave perturbations. Moreover, if the coherent Higgs oscillations didn't decay they could explain the missing mass problem of cosmology.