Does Palatini Higgs Inflation Conserve Unitarity?

Understand

In the conventional metric formulation of gravity, the Higgs Inflation model violates unitarity in the electroweak vacuum in Higgs scattering at the energy scale $\Lambda \sim M_{Pl}/\xi$, where $\xi \sim 10^4$ is the non-minimal coupling of the Higgs to the Ricci scalar.

• In the Palatini formulation it is commonly believed that $\Lambda \sim M_{Pl}/\sqrt{\xi}$, where $\xi \sim 10^{9}$.
• Here we reconsider unitarity violation in the electroweak vacuum in the Palatini formulation.
• We argue that there is no unitarity violation in Higgs scattering in the Palatini non-minimally coupled Standard Model in the electroweak vacuum at energies below the Planck scale.