| 研究実績の概要 |
I have finished the investigation of the reheating process after inflation in the mixed Higgs-R^2 model. My study can improve the observational constraint on this theoretically motivated inflation model with minimal setup within the Standard Model and general relativity. I investigated the perturbative reheating in this model where the perturbative decay of inflatons to relativistic particles plays an essential role. Such a process usually dominates the energy transfer from inflaton to radiation at late time. Besides, the perturbative reheating always occurs as long as the preheating process is not fine-tuned enough to reheating the Universe. I calculated the perturbative decay rates of inflatons and found that they differ significantly from the single-field case due to the multi-field structure. I took into account the decay rates as friction terms in the equations of motion of inflatons and solved them numerically together with the Boltzmann equation, finding that the reheating temperature is independent of the detail of preheating while the duration will differ as the efficiency of preheating changes. The reheating temperature is higher for Higgs-like parameters than for R^2-like. This result breaks the degeneracy of inflation predictions among model parameters so that more precise observation in the future can easily constrain the model parameter in this model. Confirming or ruling out this model is decisive for the question whether inflation is realized with physics beyond the Standard Model.
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