Quarks by Computer; February 1996; Scientific American Magazine; by Weingarten; 5 Page(s)

Running a supercomputer continuously for several years to generate a dozen or so results might raise a few impatient eyebrows. But to my collaborators and me, it was time well spent. The tasks we had given the machine are so complicated that they simply cannot be carried out with paper and pencil, but they address key problems in the theory of elementary particles. Calculations lasting a few years seemed reasonable.

The problems with which we were concerned arise from quantum chromodynamics, the theory governing the behavior of quarks. Formulated in the 1970s, QCD--as it is often called--describes how quarks combine in pairs or triplets to form hadrons, the class of particles that is subject to the strong nuclear force. The familiar proton and neutron belong to this family, as do more exotic kinds of particles that briefly appear in high-energy collisions in particle accelerators or in cosmic-ray showers. Experiments that scattered electrons off hadrons, which were designed to probe the hadron's internal structure, provided the initial data showing that QCD was very likely correct. The theory now represents one of the linchpins of the Standard Model of particle physics.