SCALE INVARIANCE AND VACUUM ENERGY

Abstract

The possibility of mass in the context of scale-invariant, generally covariant theories, is discussed. Scale invariance is considered in the context of a gravitational theory where the action, in the first-order formalism, is of the form [Formula: see text] where Φ is a density built out of degrees of freedom independent of the metric. For global scale invariance, a "dilaton" ϕ has to be introduced, with nontrivial potentials V(ϕ)=f1eαϕ in L1 and U(ϕ)=f2e2αϕ in L2. This leads to nontrivial mass generation and a potential for ϕ which is interesting for new inflation. Scale invariant mass terms for fermions lead to a possible explanation of the present day accelerated universe and of cosmic coincidences.