The seminar will take place from 11-12 p.m. PDT in Physics 375 North. Our speaker is Jonathan Ouellet (MIT). Details are below.

Probing Fundamental Symmetries at the Edge of Absolute Zero

• Why is there something in the universe instead of nothing?

• Does the axion solve the Strong CP problem and does it explain the dark matter abundance of the universe?

Each of these two questions brings together physics on the largest of observable scales with the behavior of particles on the smallest of scales. Why matter formed and what caused it to cluster into galaxies and stars are among the most fundamental open questions in physics today. The answers may lie in understanding the fundamental symmetries of the Standard Model (SM). In this talk, I will outline the search for Neutrinoless Double Beta (0νββ) decay, a lepton number violating decay that could help explain the matter dominance of the universe. I will present the CUORE experiment, a ton-scale bolometeric detector operating at 10 mK, that searches for this and other rare decays, and its successor, CUPID, which aims to discover 0νββ decay in the Inverted Hierarchy regime. I will then discuss the Strong CP problem – the seemingly accidental conservation of CP symmetry in the SM – how the axion solves this problem, and its recent reemergence as a leading dark matter candidate. I will describe the ABRACADABRA-10 cm demonstrator experiment at MIT and show results from its recent searches for axion dark matter. Finally, I will introduce DMRadio, a multi-phase program designed to search for the QCD axion in mass ranges lower than have ever been probed and in parameter spaces that are relevant to GUTscale theories. DMRadio aims to be a leading next-generation axion search, capable of discovering the axion all the way down to the bottom of the DFSZ band.