Observational signatures of Higgs inflation

Abstract

We investigate the dependency of Higgs inflation on the non-renormalisable matching between the low energy Standard Model limit and the inflationary regime at high energies. We show that for the top mass range m(t) greater than or similar to 171.8 GeV the scenario robustly predicts the spectral index n(s) similar or equal to 0.97 and the tensor-to-scalar ratio r similar or equal to 0.003. The matching is however non-trivial, even the best-fit values m(h) = 125.09 GeV and m(t) = 173.21 GeV require a jump delta lambda similar to 0.01 in the Higgs coupling below the inflationary scale. For m(t) less than or similar to 171.8 GeV, the matching may generate a feature in the inflationary potential. In this case the predicted values of n(s) and r vary but the model is still falsifiable. For example, a detection of negative running of spectral index at level alpha(s) less than or similar to -0.01 would rule out Higgs inflation.