Higgs-Dilaton cosmology: Universality vs. criticality

Understand

The Higgs-Dilaton model is able to produce an early inflationary expansion followed by a dark energy dominated era responsible for the late time acceleration of the Universe.

• At tree level, the model predicts a small tensor-to-scalar ratio ($0.0021\leq r \leq 0.0034$), a tiny negative running of the spectral tilt ($-0.00057 \leq dn_s/d\ln k \leq -0.00034$) and a nontrivial consistency relation between the spectral tilt of scalar perturbations and the dark energy equation of state, which turns out to be close to a cosmological constant ($0 \leq 1+w_{DE} \leq 0.014$).
• We reconsider the validity of these predictions in the vicinity of the critical value of the Higgs self-coupling giving rise to an inflection point in the inflationary potential.
• The value of the inflationary observables in this case strongly depends on the parameters of the model.