In these pictures
e- and e+
beams, perpendicular to the screen, met and
annihilated. The resulting quarks and antiquarks combined to produce
mesons and
baryons, whose tracks are shown.
On the left, three clusters, initiated by a quark,
its antiquark, and a gluon,
provide evidence for the existence of gluons. On the right, two back-to-back
clusters of particles were initiated by a quark and its oppositely moving
antiquark.
