Abstract
We discuss a simple unitarization of Higgs inflation that is genuinely weakly coupled up to Planckian energies. A large non-minimal coupling between the Higgs and the Ricci curvature is induced dynamically at intermediate energies, as a simple ratio of mass scales. Despite not being dominated by the Higgs field, inflationary dynamics simulates the `Higgs inflation' one would get by blind extrapolation of the low-energy effective Lagrangian, at least qualitatively. Hence, Higgs inflation arises as an approximate `mirage' picture of the true dynamics. We further speculate on the generality of this phenomenon and show that, if Higgs-inflation arises as an effective description, the details of the UV completion are necessary to extract robust quantitative predictions.
Highlights
JHEP09(2015)027 effective operators which change the dynamics of the Higgs modulus field for |H| > Mp/ξ
The inflationary dynamics implied by (1.2) is robust, since the Weyl transformation has the additional effect of decoupling the Higgs modulus from the rest√of the SM degrees of freedom, precisely in the ‘plateau region’ of field space, |H| ≫ Mp/ ξ
The scenario of Higgs inflation that we have described is in serious disagreement with the ‘standard rules’ of effective field theory, since it was defined by a bold extrapolation of an effective Lagrangian beyond its naive domain of applicability
Summary
We consider a simple extension of the Standard Model with one single new degree of freedom: a heavy (real) scalar φ with a (Jordan-frame) Lagrangian given by. The precise correlation between the non-minimal coupling, φ R, and the highest power of the bare potential, φ2, allows us to run a rehash of the Higgs inflation scenario, by extrapolating the Einstein-frame effective Lagrangian to the positive trans-Planckian domain φ ≫ Mp. A crucial difference with the standard HI scenario is the absence of any large dimensionless couplings in the action, in the non-minimal coupling of type (1.1). A radical violation of the unitarity constraint, in the form of a large non-minimal coupling g ≫ 1, would just reintroduce the large-ξ problem of HI into the effective UV model (2.1) Even if such a consideration runs against the main philosophy of this work, it is worth mentioning that the formal limit g → ∞ can be analysed from the standpoint of (2.1) by rescaling both the field φ → Φ/g and the mass parameter m → M/g. In this limit (2.1) becomes equivalent to Starobinsky’s model of inflation [12], with mass scale M .5
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