Mastering Nature's Strong Force

摘要

Physicists have demonstrated their grasp of the force that binds the atomic nucleus by learning how to identify the exotic particles it spawns, called glueballs. "Quark" is fanciful, "electron" is classical, but in the lexicon of elementary particle physics, "glueball" is as descriptive as it gets. Glueballs, if they really exist, are made entirely of sticky stuff—of gluons, particles that carry the strong force that binds quarks together to make up protons and neutrons. Glueballs also live up to their name by being, in the words of Princeton University theorist David Gross, "nasty objects"—short-lived, elusive, and easy to confuse with more mundane particles. Worse still, the theory that predicts glueballs, called quantum chromo- dynamics (QCD),"is a theory where you can write down the fundamental equations," says University of Chicago theorist Jonathan Rosner, "but then you have one hell of a time trying to solve them." As a result, theorists have had only the vaguest idea what a glueball should look like.