题目: Thermal production of gravitational waves in the early universe
报告人：许勋杰 副研究员 【中国科学院高能物理研究所】
时间：2025年11月3日（周一）14:00
地点：田家炳楼南楼203报告厅
邀请人：张永超
摘要: In the very early universe, when everything was extremely hot and dense, gravitons could be produced abundantly through thermal processes such as particle collisions and decays. As the universe expanded and cooled, these gravitons became highly redshifted, eventually forming a faint background of gravitational waves that still exists today. Much like the cosmic microwave background (CMB) and the cosmic neutrino background (CNB), the cosmic gravitational wave background (CGWB) is a thermal relic of the hot Big Bang. But unlike the CMB and CNB, the CGWB is highly sensitive to the maximum temperature the early universe once reached. In this talk, I will introduce this emerging topic in cosmology and share my perspective on what the CGWB could reveal about the extreme conditions of the early universe.
报告人简介：Xunjie XU (许勋杰) is a theoretical particle physicist currently working at the Institute of High Energy Physics (IHEP), Beijing, China. Before joining IHEP, he was a postdoctoral researcher at the Université libre de Bruxelles (ULB), Brussels from 2020 to 2021, and the Max-Planck-Institut für Kernphysik (MPIK), Heidelberg from 2016 to 2020. His research covers neutrino physics, BSM physics, and most recently, cosmology (info from https://xunjiexu.github.io/).