Number 252 (Story #2), December 18, 1995 by Phillip F. Schewe and Ben Stein DO GLUEBALLS EXIST? In quantum chromodynamics (QCD), the theory of the strong interaction, the force between quarks is carried by gluons, just as the electromagnetic force between electric charges is carried by photons. Since gluons have a "color charge" (analogous to electric charge) they can bind to each other as well as to quarks. However, telling such gluon states, or glueballs, from other particles is sticky. Some physicists approach the problem by inventing an Erector-Set world in which quarks sit at discrete sites in a cubic lattice. Work in this area is computer-intensive since the interactions of many particles over the interstices of a fine grid (the finer the better) must be followed through myriad iterations. In what they call "the largest single numerical calculation in the history of computing," three IBM physicists have now derived the mass of what should be the lightest glueball. Their value, 1707 MeV, is very close to that of an already-observed particle, f(1710). (J. Sexton et al., Physical Review Letters, 18 December 1995.)