Particle physicists offer a road map for the next decade

•  DENNIS OVERBYE, KATRINA MILLER

Particle physicists should begin laying the groundwork for a revolutionary particle collider that could be built on American soil, a committee of scientists wrote in a draft report on the future of particle physics released on Thursday. The machine would collide tiny, point-like particles called muons, which resemble electrons but are more massive. Muons provide more bang for the buck than the protons used in the Large Hadron Collider at CERN, and would push the search for new forces and particles deeper than ever into the unknown.

The siting of such a project, perhaps at the Fermi National Accelerator Laboratory in Illinois, would restore American particle physics to a position of pre-eminence that was ceded to Europe in 1993 when Congress canceled the giant Superconducting Super Collider. But it will take at least 10 years to demonstrate that the muon collider could work and how much it would cost.

“This is our muon shot,” the committee, charged with outlining a vision for the next decade of American particle physics, said in a draft report titled “Exploring the Quantum Universe: Pathways to Innovation and Discovery in Particle Physics.” The draft is being presented and discussed at a meeting in Washington, D.C., on Thursday and Friday, and at Fermilab next week.

The draft report also highlighted a need to invest in next-generation experiments probing the nature of subatomic particles called neutrinos; the cosmic microwave background, relic radiation from the Big Bang; and dark matter, the gravitational glue holding galaxies together. The panel also recommended participating in a future facility in either Europe or Japan, dedicated to studying the Higgs boson, the discovery of which in 2012 was key for understanding how other particles get their mass.

“The size of the universe we now see as 14 billion light-years across was actually smaller than the size of a nucleus” early in cosmic time, said Hitoshi Murayama, a physicist at the University of California, Berkeley, who led the committee. “So our field is actually not just looking for the fundamental constituents, but getting a bigger picture of how the universe works as whole.”

The committee, formally known as the Particle Physics Project Prioritization Panel, or P5, was tasked by the U.S. Department of Energy and the National Science Foundation to lay out a road map for the future of the field. The three-year process began by soliciting input from the particle physics community at large, and the final report will serve as a recommendation for what national agencies should prioritize over the next decade.

The last P5 report, “Building for Discovery: Strategic Plan for U.S. Particle Physics in the Global Context,” was published in 2014 on the heels of the Higgs boson discovery. That was a tremendous success for the Standard Model, a suite of quantum equations that explains everything that scientists know and test in the laboratory about the forces and particles in nature, and which has reaped numerous Nobel Prizes for its originators.