The Standard Model of particle physics has one final renormalisable parameter whose value has not yet been measured: The (non-minimal) coupling between spacetime curvature and the Higgs field. It has practically no effect today, which is why it cannot be measured in experiments, but it was very important in the early universe when the spacetime was highly curved. I discuss the effect of the coupling on the Higgs dynamics during and after inflation and its implications for vacuum stability. In the minimal scenario with no new physics above the electroweak scale these considerations improve the LHC constraints on its value by 15 orders of magnitude and exclude the minimally coupled case.
