US Particle Physics Leaders Agree on Priorities for Next Decade

The High Energy Physics Advisory Panel approved a report last week that sets an agenda for U.S. particle physics research over the next decade.

Developed by a HEPAP subcommittee known as the Particle Physics Project Prioritization Panel (P5), the report identifies top priorities for research and facilities construction under a baseline budget scenario that matches the targets of the CHIPS and Science Act then keeps up with estimated inflation of 3% and a “less favorable” scenario of only 2% annual growth.

In both scenarios, the top priorities are to complete major projects that are already underway, namely the Vera C. Rubin Observatory, the first phase of the international DUNE neutrino experiment and the PIP-II accelerator upgrade at Fermilab, and the high-luminosity upgrades to CERN’s Large Hadron Collider, as well as a suite of midscale projects.

In the baseline scenario, the report’s next priorities are to complete the CMB-S4 multi-telescope array, a “re-envisioned” second phase of DUNE with accelerated beam upgrades and a third detector at the experiment’s “far” site in South Dakota, a “factory” outside the U.S. focused on researching Higgs bosons, a third-generation dark matter detector, and an upgrade to the IceCube neutrino detector at the South Pole.

The report also recommends creating a small project program at DOE and increasing funding for accelerator and instrumentation R&D. With an eye to the longer term, it recommends beginning “vigorous R&D” toward the development of a 10 tera-electron-volt proton or muon collider, with the aim of enabling major test facilities and demonstrator facilities within the next 10 years. It highlights the possibility of upgrading the Fermilab accelerator complex to host a muon collider, a so-called “muon shot” that would fulfill the long-term ambition of hosting a major international collider facility in the U.S.

In the less favorable budget scenario, the report recommends proceeding with CMB-S4 and IceCube-Gen2 without reductions in scope, but limiting the DUNE upgrades and paring back U.S. contributions to an off-shore Higgs factory and a third-generation dark matter experiment. It warns that this scenario could lead to the loss of U.S. leadership in many areas and damage the reputation of the U.S. as a reliable international partner.