Dynamical measure and field theory models free of the cosmological constant problem

TL;DR

This paper introduces field theory models that naturally have zero vacuum energy without fine tuning, addressing the cosmological constant problem while supporting inflation and gauge symmetry breaking.

Contribution

It presents novel gravitational models with a dynamical measure that solve the cosmological constant problem and are compatible with inflation and gauge theories.

Findings

Vacuum energy density is zero without fine tuning.

Models support inflationary scenarios.

Compatibility with gauge theories and classical tests.

Abstract

Summary of abstract Field theory models including gauge theories with SSB are presented where the energy density of the true vacuum state (TVS) is zero without fine tuning. The above models are constructed in the gravitational theory where a measure of integration \Phi in the action is not necessarily \sqrt{-g} but it is determined dynamically through additional degrees of freedom. The ratio \Phi/\sqrt{-g} is a scalar field which can be solved in terms of the matter degrees of freedom due to the existence of a constraint. We study a few explicit field theory models where it is possible to combine the solution of the cosmological constant problem with: 1) possibility for inflationary scenario for the early universe; 2) spontaneously broken gauge unified theories (including fermions). The models are free from the well known problem of the usual scalar-tensor theories in what is concerned with the classical GR tests. The only difference of the field equations in the Einstein frame from the canonical equations of the selfconsistent system of Einstein's gravity and matter fields, is the appearance of the effective scalar field potential which vanishes in TVS without fine tuning.