Imprints of Ultralight Scalars across Cosmological HistoryConfirmed

by Tien-Tien Yu (University of Oregon)

Tuesday May 26, 2026, 1:00 PM → 2:30 PM America/Toronto

PI/3-394 - Skyroom (Perimeter Institute for Theoretical Physics)

Ultralight scalar fields present a compelling dark matter candidate that can imprint potential signatures on observables spanning from the early Universe to today. In this talk, I will explore the implications of scalar dark matter that couples quadratically to the Standard Model. Such couplings induce temporal variations in the fundamental constants, leading to measurable effects on Big Bang Nucleosynthesis, the Cosmic Microwave Background, and equivalence principle tests. I will discuss how these changes influence the light element abundances and the CMB power spectrum, and how current cosmological data constrain this class of dark matter models. In addition, I will discuss the quadratically-coupled scalar dark matter manifests itself in equivalence principle tests.