Cosmological constant in scale-invariant theories

TL;DR

This paper explores how small positive cosmological constants can be integrated into scale-invariant models, leading to specific particle mass relations and a metastable electroweak vacuum, with dilaton mass generated at two-loop level.

Contribution

It demonstrates the construction of phenomenologically consistent scale-invariant models with a small cosmological constant and analyzes their implications for particle masses and vacuum stability.

Findings

Dilaton mass generated at two-loop level.

Electroweak vacuum is metastable but long-lived.

Models require specific relations between particle masses.

Abstract

The incorporation of a small cosmological constant within radiatively-broken scale-invariant models is discussed. We show that phenomenologically consistent scale-invariant models can be constructed which allow a small positive cosmological constant, providing certain relation between the particle masses is satisfied. As a result, the mass of the dilaton is generated at two-loop level. Another interesting consequence is that the electroweak symmetry-breaking vacuum in such models is necessarily a metastable `false' vacuum which, fortunately, is not expected to decay on cosmological time scales.