报告题目：Spectral Representation of Cosmological Correlators

报  告 人：Denis Werth (Institut d'Astrophysique de Paris, Sorbonne Université)

报告时间：2024年11月28日13：30  

报告地点：物理楼W105

内容摘要：Cosmological correlators are significantly more complex than their flat-space analogues, such as tree-level scattering amplitudes. While these amplitudes have rather simple analytic structure and clear factorisation properties, cosmological correlators often feature branch cuts and lack neat expressions.In this talk, after a pedagogical introduction to observational, phenomenological and theoretical aspects of cosmological correlators meant for the broad audience, I will present a new off-shell perturbative method to study and compute cosmological correlators. Using a spectral representation of massive cosmological propagators that encodes spontaneous particle production through a suitable pole prescription, I will show in detail how such approach not only makes the origin of the correlator singularity structure and factorisation manifest, but also renders practical analytical computations more tractable. This approach explicitly shows that complex correlators are constructed by gluing lower-point off-shell correlators, and suggests that spectral methods hold promise for developing cosmological recursion relations, further connecting techniques from modern scattering amplitudes to cosmology.This talk will be mainly based on [arXiv:2409.02072].

报告人简介：Denis Werth is currently a PhD student at the Institut d'Astrophysique de Paris (IAP) and Sorbonne University, in France. He received his master degree at Ecole Normale Supérieure, Paris in 2021. His research interests lie at the interface between primordial cosmology and theoretical high-energy physics. He sees the early Universe as the ultimate laboratory where high-energy theories can be tested on the most fundamental scales. He develops new methods to deepen our understanding of the Universe's origins using modern quantum field theory approaches. He is particularly interested in using cosmological observations to search for evidence of new physics.