Gravitational dynamics in Higgs inflation: Preinflation and preheating with an auxiliary field

The dynamics of both the preinflationary and the preheating epochs for a model consisting of a Higgs inflaton plus an additional auxiliary field are studied in full General Relativity. The minimally coupled auxiliary field allows for parametric-type resonances that successfully transfer energy from the inflaton condensate to particle excitations in both fields. Depending on the interaction strengths of the fields, the broad resonance periods lead to structure formation consisting of large under/overdensities, and possibly the formation of compact objects. Moreover, when confronting the same model to multifield inhomogeneous preinflation, the onset of inflation is shown to be a robust outcome. At relatively large Higgs values, the nonminimal coupling acts as a stabilizer, protecting the dynamics of the inflaton, and significantly reducing the impact of perturbations in other fields and matter sectors. These investigations further confirm the robustness of Higgs inflation to multifield inhomogeneous initial conditions, while putting in evidence the formation of complex structures during the reheating.

Automated summary

This study investigates the dynamics of both the preinflationary and preheating epochs in a model consisting of a Higgs inflaton and an additional auxiliary field in full General Relativity. The presence of the auxiliary field allows for successful energy transfer from the inflaton condensate to particle excitations in both fields through parametric-type resonances. The interaction strengths of the fields determine the formation of structures, including large under/overdensities and possibly compact objects.