The future of particle physics

When a U.S. government advisory panel met over the past two years to prioritize research projects in the field of particle physics, Virginia Tech Department of Physics Professor Patrick Huber played a key role.

The significance of particle physics

“We are trying to understand what holds the world together at the smallest scale you can observe,” Huber said. “We have learned to gain that understanding, you also have to look to the cosmos at the largest scales to provide answers.”

Huber, a William E. Hassinger, Jr. Senior Faculty Fellow, is director of the Center of Neutrino Physics. His expertise lies in neutrinos, the most abundant particles with mass in the universe. Neutrinos are created when atomic nuclei come together, like on the sun, or when they decay, like in a nuclear reactor.

Why it matters

Known as the P5, the Particle Physics Project Prioritization Panel, through its sponsoring organization the High Energy Physics Advisory Panel, recommends which projects the U.S. Department of Energy and the National Science Foundation should fund in the coming decade. The recommendations are just that, but the funding agencies traditionally give them great weight.

Billions of dollars of federal government funding are at stake.

“I’m excited about this. I think if we can follow the trajectory of this plan, it will put the U.S. in a significant leadership position in central parts of particle physics. Overall, for global particle physics it ensures we can keep making progress,” Huber said.

How it worked

In 2022, the American Physical Society, which organizes the P5, invited any interested physicist to participate in a two-year process that culminated in a 10-day summit called Snowmass in Seattle. More than 1,000 physicists made the trip. The question on the table: If we had infinite resources, which projects should we explore, which technologies should we pursue, and what facilities should we build?

The P5 members, including Huber, then took that wish list, reviewed it within an estimated available budget, and prioritized the work. They held eight, week-long meetings to sort through the suggestions.

“Needless to say, this is like a Christmas shopping list,” Huber said. “The wish list is longer than what we can afford.”

The big picture (of the smallest masses)

A major recommended thrust of the P5 report is to provide funding that would enable physicists to finish major research projects that are underway and have produced noteworthy results. It recommends:

• Ongoing support for the Deep Underground Neutrino Experiment at Fermilab in Illinois. “This is obviously near and dear to my heart” said Huber, a neutrino physicist. “It needs a second phase to fulfill its potential.”
• A network of ground-based telescopes called CMB-4 designed to observe the cosmic microwave background. “The hope is we can find signs of the earliest times in the universe,” Huber said, “when the universe was maybe the size of a pineapple.”
• The expansion of the South Pole’s neutrino observatory, an international collaboration known as IceCube-Gen2.
• A “Higgs factory,” an international collaboration to reveal the secrets of the Higgs boson, an elementary particle in standard physics.
• A dark matter detection experiment called Ultimate Generation 3.

In addition to the big projects, Huber said the P5 report recommends a broad program that could seed ideas that pay off down the road.

“There’s a portfolio of small and agile projects,” he said, “which is really important to give people to the chance to have ideas and try them out and that way broaden both our technology and our science for future work.”

The report also recommends a vigorous research and development program toward even more powerful particle accelerators, which may lead to a muon collider on the Fermilab site.

“Continued and increased investment in developing the workforce, broadening engagement, and supporting ethical conduct are the underpinning for the entire science program,” Huber said.