GUT-scale axion searches with DMRadio

by Nicholas Marcos Rapidis (Stanford University)

Wednesday 10 Dec 2025, 12:30 → 14:30 America/Los_Angeles

48/2-224 - Madrone (SLAC)

The nature of dark matter and the strong CP problem of QCD remain two of the most significant unanswered problems of physics. The axion is a promising solution to both problems, as it provides a natural resolution to the strong CP problem while having favorable production mechanisms in the early universe that would allow it to constitute the dark matter. In this talk, we first present an overview of axion experiments searching for dark matter and discuss the fundamental limits on their sensitivity, particularly in relation to the standard quantum limit. We then present the operational principles of the DMRadio series of experiments, a series of experiments searching for electromagnetically coupled QCD axions in the 0.4-800 neV range. We discuss the requirement of quantum sensing below the standard quantum limit, and our understanding of axion electrodynamics in their role of enabling the ultimate low-mass axion experiment, DMRadio-GUT. This experiment would probe axions with symmetry breaking scales near the grand unified theory (GUT) energy scale. We also present the status of DMRadio-50L, an ongoing experiment at Stanford University.