© David Kaplan.
When quarks and anti-quarks and gluons are produced in high-energy collisions, they move apart from each other at nearly the speed of light. The immediate response is to start pulling more color-charged particles out of the vacuum, mostly in the direction the original particle is moving. Thus, the signature of a high-energy quark or gluon produced in a particle collider is a spray of hadrons, most confined to a small cone, or jet, whose vertex is at the collision point. In the diagram above, quarks are represented by straight green lines and gluons are red wiggly lines. Time increases to the right. (Unit: 2)