Fundamental Physics with Cosmic Microwave Background Observations by Prof. Masashi Hazumi KEK, Japan

Particle cosmology aims to uncover the fundamental laws of physics that govern the Universe. Our research today is driven by five outstanding mysteries: cosmic inflation, baryon asymmetry, neutrino properties, dark matter, and dark energy. In addition, two recent observational hints—possible parity violation in cosmological signals and indications of dynamical dark energy—suggest that new physics may be within reach. Resolving any of these questions would profoundly transform particle physics and our understanding of the Universe. Among the many observational probes, measurements of the cosmic microwave background (CMB) play a key role. After briefly reviewing past CMB observations, I will introduce the projects I am currently involved in, with particular emphasis on the Simons Observatory and LiteBIRD. I will conclude by discussing the emerging synergy between CMB measurements and gravitational-wave observations, and how their combination may open new windows onto fundamental physics. "