NRC Group Offers Views on Future of High Energy Physics

“The U.S. elementary-particle physics community has been redefining its future in the wake of the SSC cancellation and learning the lessons inherent in its demise. This report is part of that process.” --Committee on Elementary-Particle Physics

As High Energy Physics in the U.S. moves from post-SSC turmoil to anticipation of operations at the Fermilab Main Injector and other facilities, and construction of the LHC in Geneva, several reports are available to guide the way. One, by a Subpanel of DOE’s High Energy Physics Advisory Panel (HEPAP), was presented at a HEPAP meeting last month (see FYI #34 .) Additionally, Committee on Elementary-Particle Physics of the National Research Council’s (NRC) Board on Physics and Astronomy has produced a 173-page report entitled, “Elementary-Particle Physics: Revealing the Secrets of Energy and Matter.” The NRC draft looks at progress in the field over the last 20 years and identifies “key physics objectives for the coming decades.” Its recommendations are in strong agreement with those made by the HEPAP Subpanel.

The report finds high energy physics “poised on the threshold of a new energy frontier.” A new era of research, it says, “will begin in the next few years as experiments that should decisively answer many of the long-standing questions come on-line. Key U.S. facilities - the Positron-Electron Project II (PEP-II) and the CESR upgrade in addition to the Main Injector - will begin operations in the next few years with greatly enhanced capabilities...” While some of the questions (such as CP violation, rare transitions and the nature of dark matter) can be addressed by facilities below the energy frontier, others (such as the nature of mass) will require “experiments at higher energies than those to which experimenters now have access.” The recommendations are therefore separated into two categories: “first, those relevant to the energy frontier, and second, one concerning important studies that are best done elsewhere. Both are essential to a balanced program.”

According to the report, “the committee...believes that the highest priority is full involvement in TeV mass scale physics at large facilities uniquely suited to this purpose. This involvement includes exploiting the Fermilab Collider (presently the highest-energy facility extant); strong participation in construction of and research at the Large Hadron Collider (LHC) being built in Europe; and taking a leadership role in a future forefront international facility, possibly to be built in the United States.” This leads to its recommendations for facilities at the energy frontier.

1. RECOMMENDATIONS CONCERNING THE HIGH-ENERGY FRONTIER: 1.a. Recommendation on the Fermilab Collider Facility: “The United States should capitalize on the potential of the Fermilab Collider Facility while it has unique capabilities for investigations of high mass scale physics.” 1.b. Recommendation on the Large Hadron Collider: “The committee enthusiastically endorses U.S. participation in the Large Hadron Collider project as a vital and essential component of the U.S. experimental particle physics program.” 1.c. Recommendations on the Next Generation of Accelerators: 1.c.1. “The committee recommends support of an international effort leading toward a complete design and cost estimate of an electron linear collider that would be able ultimately to reach a center-of-mass energy of 1.5 TeV...” 1.c.2. “R&D targeted at developing the technologies for muon and very large hadron colliders should be vigorously pursued.” “Other problems of great importance to the understanding of elementary particles do not require the highest energies for elucidation,” the report adds. Thus the committee also makes a recommendation for physics at energies less than the frontier.

2. RECOMMENDATIONS FOR ADDRESSING IMPORTANT FUNDAMENTAL PHYSICS PROBLEMS BELOW THE TeV MASS SCALE: “The committee recommends strong support for a well-targeted program to study the fundamental particle physics that can best be explored with experiments below the TeV scale.” Additionally, the committee warns, “Because of limitations in resources for the field worldwide, in the future only initiatives that have the most promise for scientific advancement should be undertaken.”

Currently, the Executive Summary of the report, which includes the recommendations, is available on the NAS Website under “Reports” at: http://www.nas.edu/bpa