Inflation at the GUT scale in a Higgsless universe

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Abstract
We revisit inflation in induced gravity. Our focus is on models where the low scale Planck mass is completely determined by the breaking of the scaling symmetry in the field theory sector. The Higgs-like field which breaks the symmetry with a GUT-scale vacuum expectation value (vev) has nonminimal couplings to the curvature, induced by the gravitational couplings of the other light fields in the theory, so that its vev controls the gravitational strength. This field can drive inflation and give a low energy universe in very good agreement with the cosmological observations. The low energy dynamics of the standard model cannot be unitarized by the Higgsflaton, which decouples from the low energy theory, both because it picks up a large mass and because its direct couplings to the low energy modes are weakened. Instead, the short distance behavior of the standard model may be regulated by the dynamics of other light degrees of freedom, such as in Higgsless models.