报告题目： One-loop tensor power spectrum from an excited scalar field during inflation
报 告 人： 太田敦久（博士），太阳成集团
邀 请 人：周思益
时 间： 2023年8月26号（星期六）17:00
地 点： 腾讯会议 和 0638太阳集团
Abstract: Loop corrections to the inflationary primordial tensor power spectrum are typically assumed to be suppressed by the Hubble-to-Planck mass ratio. Therefore, the tree-level analysis is generally considered sufficient. Recent advancements in cosmological observations suggesting primordial black holes (PBHs) could provide fresh insights into this situation. PBHs can originate from large curvature perturbations in the past, implying the presence of excited fields during inflation. These fields might contribute significantly to the loop effect. In this presentation, using the in-in formalism, I evaluate the 1-loop tensor power spectrum in the presence of an excited spectator scalar field during inflation. We found that the super-horizon primordial power spectrum of the tensor mode could be either scale-invariantly enhanced or reduced by the loop effects of a sub-horizon scalar field. This possibility opens up new avenues for investigating the small-scale physics of the early Universe through gravitational wave measurements at all scales.
