On UV-completion of Palatini-Higgs inflation

Abstract

We investigate the UV-completion of the Higgs inflation in the metric and the Palatini formalisms. It is known that the cutoff scales for the perturbative unitarity of these inflation models become much smaller than the Planck scale to be consistent with observations. Expecting that the low cutoff scale originates in the curvature of a field-space spanned by the Higgs fields, we consider embedding the curved field-space into a higher dimensional flat space and apply this procedure to the metric-Higgs and the Palatini-Higgs scenarios. The new field introduced in this way successfully flattens the field-space and UVcompletes the Higgs inflation in the metric formalism. However, in the Palatini formalism, the new field cannot uplift the cutoff up to the Planck scale. We also discuss the unavoidable low cutoff in the Palatini formalism in the context of the local conformal symmetry.

Field redefinitions, perturbative unitarity and Higgs inflation

“…Indeed, it was confirmed in [13] that the interactions of the NG bosons also lead to the cutoff (1.2). Since then, the validity of this result has been established using various methods [14][15][16][17] (see also [18,19]).…”