Cosmological implications of a scale invariant standard model

Abstract

We consider a generalization of the standard model of particle physics such that it displaysglobal scale invariance. The gravitational action is also suitably modified to respect thissymmetry. This model is interesting since the cosmological constant term is absent in theaction. We find that the scale symmetry is broken by the recently introduced cosmologicalsymmetry breaking mechanism. This simultaneously generates all the dimensionfulparameters such as Newton’s gravitational constant, the particle masses and the vacuum ordark energy. We find that in its simplest version the model predicts the Higgs mass to bevery small, which is ruled out experimentally. We consider a further generalization of themodel such that it displays local scale invariance. This model was proposed earlier byCheng. In this case the Higgs particle disappears from the particle spectrum andinstead we find a very massive vector boson. Hence the model gives a consistentdescription of particle physics phenomenology as well as fitting the cosmological darkenergy.