A heatwave affair: mixed Higgs-R2 preheating on the lattice

• Fedor Bezrukov (University of Manchester)

We use lattice methods to perform the first nonlinear study of preheating in R2-healed Higgs inflation for "R2-like" parameters 1.1×109 and 1.8×109 where the curvature-squared coupling β and nonminimal coupling ξ of the Higgs field contribute similarly to the CMB scalar perturbations. Preheating occurs first through tachyonic production of Higgs bosons, and later scattering off the homogeneous inflaton field. We generalise our results to "Higgs-like" parameters with smaller β, where observables saturate the bound of instantaneous preheating. All predictions for the spectral index and tensor-to-scalar ratio lie within the 1σ region of measurements by the Planck satellite, but a future ground-based experiment optimised for 21 cm tomography may be able to discriminate the mixed Higgs-curvature inflation from the pure Higgs and R2 theories.