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v3.3.3-pre
14:00 Matthew Moschella, Princeton
Title: Axion Comagnetometry
Abstract: If dark matter is an ultralight axion-like particle, the gradient of its classical field can be detected in precision atomic experiments, including helium-potassium comagnetometers. In this talk, I will discuss an ongoing re-analysis of existing comagnetometer data, which will yield world-leading sensitivity to axions in the mass range from 10^-17 to 10^-12 eV that couple to neutrons. Proper interpretation of this data requires a careful treatment of the dark matter velocity distribution, which leads to stochastic fluctuations of the signal amplitude. I will introduce a complete statistical treatment for these stochastic effects, which has implications for any experiment that is sensitive to the gradient of the axion field.
14:30 David Dunsky, Berkeley
Title: Shocking Signals from CHAMP Cosmic Rays
Abstract: Cosmological relics with miniscule electric charges are well motivated in particle physics through kinetic mixing between our photon and a dark photon, and from cosmology as a way to thermally produce dark matter in the early universe. Despite their small electric charge, such thermal relics can interact with the Milky Way environment in surprising ways. I will discuss the thermalization of CHarged Massive Particles (CHAMPs) with the interstellar medium, their diffusion through inhomogeneous magnetic fields in the Milky Way, and Fermi acceleration by supernova shock waves. The Fermi accelerated CHAMPs form a component of cosmic rays that are able to reach underground detectors and produce unique experimental signatures typically absent from dark matter moving at virial speeds. I will discuss stringent bounds on the fraction of dark matter that can be CHAMPs from signals in nuclear/electron recoil experiments, ionization detectors, and Cherenkov light experiments.