The direct coupling between the Higgs field and the spacetime curvature, if finely tuned, is known to stabilize the Higgs boson mass. The fine-tuning is soft because the Standard Model (SM) parameters are subject to no fine-tuning thanks to their independence from the Higgs-curvature coupling. This soft fine-tuning leaves behind a large vacuum energy $\propto \Lambda_{ \rm UV}^4$ which inflates the Universe with a Hubble rate $\propto \Lambda_{ \rm UV}$, $\Lambda_{ \rm UV}$ being the SM ultraviolet boundary. This means that the tensor-to-scalar ratio inferred from cosmic microwave background polarization measurements by BICEP2, Planck and others lead to the determination of $\Lambda_{ \rm UV}$. The exit from the inflationary phase, as usual, is accomplished via decays of the vacuum energy. Here we show that, identification of $\Lambda_{ \rm UV}$ with the inflaton, as a sliding UV scale upon the SM, respects the soft fine-tuning constraint and does not disrupt the stability of the SM Higgs boson.
Categories: hep-ph gr-qc hep-th