报告题目:Nonlinearity in the curvature perturbation

报告人：皮石 副研究员（中国科学院理论物理研究所）

报告时间：2023年8月15日（周二）下午 15:30-17:00

报告地点：浙江工业大学理学楼A 二楼师生活动中心

摘 要 (Abstract): During inflation, the quantum fluctuations of the inflaton field converts to the curvature perturbation, which seeds the cosmic microwave background anisotropies and the large-scale structures. On small scales, large curvature perturbation can generate primordial black holes (PBHs), of which the abundance depends crucially on the high tails of the probability distribution function (PDF) of the curvature perturbation. Therefore, the fully nonlinear relation between the curvature perturbation and the (usually Gaussian) inflaton fluctuation is crucial. In our recent paper, we found that in general the curvature perturbation is expressed in terms of a sum of logarithmic functions of the inflaton field fluctuation, while each logarithmic expression has a dual expression due to the second-order nature of the equation of motion. We clarified the condition under which one single logarithm dominates. Our formula unifies all previous works on the fully nonlinear PDFs of the curvature perturbation, and reveals new analytically solvable models. Our result is a firm step toward the accurate calculation of the formation of PBHs and sclar-induced GWs.

报告人简介(Bio): 皮石，2013年在北京大学物理系获得理论物理专业博士学位。之后在韩国亚太理论物理中心(APCTP)、中国科学院理论物理研究所、日本京都大学基础物理学研究所(YITP)、日本东京大学卡弗理数物连携宇宙研究机构(Kavli IPMU)进行博士后研究。2020年起在中国科学院理论物理研究所工作，任副研究员、博士生导师。主要从事宇宙学微扰论、暴胀宇宙学、引力理论、以及背景引力波方面的研究。近年来他的研究兴趣集中于利用随机引力波背景探测早期宇宙，在PRL,PRD,SCPMA,JCAP等国际学术期刊上发表论文30余篇

邀请人:王安忠 教授