Speaker: Dong-Gang Wang

From the Cosmological Bootstrap to CMB Observations

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, after a brief review, 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 data analysis of these new templates using the latest Planck observations. The analysis here gives us the stringent constraints on cosmological collider signals, and also sets the stage for probing these signals in future surveys.