Jet

A jet is a collimated spray of particles (mainly hadrons) produced in a high-energy particle collision. Jets form around the direction of a high-energy quark or gluon, as these fragment and hadronize almost immediately after being produced. Defining what constitutes a jet is nontrivial. An adequate jet definition provides a common language for theory and experimental measurements, and allows meaningful comparison of them. Analyses often choose the definition with the most suitable properties for the given situation.

At hadron colliders, jets are produced at very high rates. This is due to the presence of quarks and gluons in the initial state of the collisions and the high strength of the strong interaction at modern collision energies.