Princeton University/Institute for Advanced Study Early Universe/Cosmology Lunch Discussion

Organizers are Jo Dunkley, Princeton University, and Matias Zaldarriaga, Institute for Advanced Study. The lunch will be held either at Princeton University or the Institute for Advanced Study. Check the calendar for the meeting location. This week's meeting is at the Institute for Advanced Study. Attendees can bring their own lunch or stop at the IAS Dining Hall. The West Seminar room is in a building which is a short walk from the main dining area. ABSTRACT: Neutrinos and new light particles, which arise in many extensions of the Standard Model of particle physics, are an important probe of the (thermal) history of the universe. However, they are hard to detect in terrestrial experiments due to their weak couplings to ordinary matter. On the other hand, the high temperatures in the early universe allow an efficient production of even very weakly coupled particles. I will discuss how measurements of the cosmic microwave background and the large-scale structure of the universe, e.g. by Planck, CMB-S4 and DESI, can shed new light on the properties of neutrinos (beyond their masses) and on the possible existence of other light relics. In particular, I will motivate certain observational thresholds and highlight some of their direct implications for physics beyond the Standard Model. I will also present the first measurement of the cosmic neutrino background as imprinted in the clustering of galaxies measured by BOSS.