Gauge Unified Theories without the Cosmological Constant Problem

Abstract

We study gauge theories in the context of a gravitational theory without the cosmological constant problem (CCP). The theory is based on the requirement that the measure of integration in the action is not necessarily $\sqrt{-g}$ but it is determined dynamically through additional degrees of freedom. Realization of these ideas in the framework of the first order formalism solves the CCP. Incorporation of a condensate of a four index field strength allows, after a conformal transformation to the Einstein frame, to represent the system of gravity and matter in the standard GR form. Now, however, the effective potential vanishes at a vacuum state due to the exact balance to zero of the gauge fields condensate and the original scalar fields potential. As a result it is possible to combine the solution of the CCP with: a) inflation and transition to a $\Lambda =0$ phase without fine tuning after a reheating period; b) spontaneously broken gauge unified theories (including fermions). The model opens new possibilities for a solution of the hierarchy problem.