Title: From the Cosmological Bootstrap to CMB Observations

Speaker: Dong-Gang Wang，University of Cambridge

Time: 02:00 pm, Apr.18th，2024

Venue: C302, New Science Building

Abstract: Cosmological correlation functions contain valuable information about the primordial Universe, with possible signatures of new massive particles at very high energies. Recent advances of the “cosmological bootstrap” program, bring new perspectives and powerful tools to study these observables. In this talk, I will systematically classify inflationary three-point correlators using the bootstrap method, where we derive a complete set of scalar bispectra from contact, massive exchange and massless exchange diagrams. Guided by this general form of predictions, we propose a set of bispectrum templates that incorporate the distinctive signatures of cosmological colliders. Our consideration includes the oscillatory signals in the squeezed limit, the angular dependence from spinning fields, and several new shapes from nontrivial sound speed effects. Then with the recently developed pipeline CMB-BEST, we perform the first comprehensive CMB observational search of these new templates in the latest Planck data. The analysis here gives us the stringent constraints on cosmological collider signals, and also sets the stage for probing these signals in future surveys.

Bio: Dong-Gang Wang is a postdoctoral researcher as a Rubicon Fellow at the Department of Applied Mathematics and Theoretical Physics in the University of Cambridge, UK. Before that, he did his PhD in Leiden University in the Netherlands as a de Sitter Fellow from 2016 to 2020. Before that, he was a master student in USTC from 2013 to 2016. His research mainly focuses on an emerging interdisciplinary direction that applies theoretical methods of high energy physics in the studies of the primordial Universe.