Overview Talk: Prospects for Direct Detection of Low-Mass Dark Matter – Slides
Kathryn Zurek, Fermilab Wine and Cheese, June 7, 2019
Provides an overview of near-term experimental prospects in combination with some of the underlying theoretical motivations for light dark matter and complementary constraints.
Executive Summary
The workshop gathered ~70 of the most active experimentalists and theorists in the world in the subject of searching for sub-GeV dark matter particles, along with scientists and engineers from material sciences and quantum sciences. The breadth of ideas presented for both experimental searches and theories over the 4 days of the workshop was stunning and the discussions in, and outside of, the sessions were stimulating. The workshop recaptured the excitement from the early days of dark matter experiments, with plans now to cover a much bigger range of dark matter masses (1 keV to 1 GeV). The light dark matter theory ‘freeze-out / freeze-in’ framework is now very well developed and flourishing with specific models that were presented.
There were at least two dozen experimental approaches to sub-GeV dark matter presented at the workshop, many that spring from recent materials science research. These include already-established techniques and materials, as well as exciting new technologies. There is a clear path to covering MeV to GeV dark matter particle masses with at least an order of magnitude improvements in sensitivity over the next few years. Numerous methods were proposed to extend this reach down to keV masses. In a funding-limited national climate, many of these ideas will not survive. But the community needs to ensure that enough R&D funding is available to explore the most promising ideas and develop them into a suite of experiments. As choices are being made, the community also needs to take a hard look at promised sensitivities compared with those actually achieved. Guidance from the theoretical community will continue to be important as this new field progresses. It looks likely that the generic freeze-out dark matter abundances will betestable over much of the parameter space in the next three years. It will likely take much longer to fully-probe freeze-in scenarios.
Everybody attending the workshop fervently believes that particle dark matter will eventually be detected. Direct detection, although necessarily underground experiments, and axion experiments are still the most likely ways to convincingly demonstrate that particle dark matter has been discovered. Signals from indirect detection experiments, colliders and accelerators will always be harder to definitively ascribe to dark matter.
The consensus of the participants was that the workshop was very valuable as a way to bring everybody up to speed on all of the approaches to sub-GeV dark matter and to foster interactions among the participants. We believe that a workshop on this topic with a similar format should be held in about two years.