Unified gauge models and one - loop quantum cosmology

This paper studies the normalizability criterion for the one-loop wave function of the universe in a de Sitter background, when various unified gauge models are considered. It turns out that, in the absence of interaction between inflaton field and other matter fields, the supersymmetric version of such unified models is preferred. By contrast, the interaction of inflaton and matter fields, jointly with the request of normalizability at one-loop order, picks out non-supersymmetric versions of unified gauge models. The investigations in modern cosmology have been devoted to two main issues. On one hand, there were the attempts to build a quantum theory of the universe with a corresponding definition and interpretation of its wave function [1, 2]. On the other hand, the drawbacks of the cosmological standard model motivated the introduction of inflationary scenarios. These rely on the existence of one or more scalar fields, and a natural framework for the consideration of such fields is provided by the current unified models of fundamental interactions [3]. The unification program started with the proposal and the consequent experimental verification of the electroweak standard model (SU(3)C ⊗ SU(2)L ⊗ U(1)Y ), and has been extended to other simple gauge groups, like SU(5), SO(10) and E6. All of them in fact, even if with