In
particle physics, a
three-jet event is an
event with many particles in final state that appear to be clustered in three
jets. A single jet consists of particles that fly off in roughly the same direction. One can draw three cones from the interaction point, corresponding to the jets, and most particles created in the reaction will appear to belong to one of these cones. These events are currently the most direct available evidence for the existence of
gluons, and were first observed by the
TASSO experiment at the
PETRA accelerator at the
DESY laboratory.