On particle--like jets

Under which conditions does a jet appear as a particle--like signal from the hidden realm of quarks and gluons? Motivated by this question jet clustering conditions are formulated, in order to characterize jet clustering algorithms, which can be used for a determination of particle--like jets. Jets are understood as particle--like, if they behave like free particles. The simplest solution to the jet clustering conditions leads to a new jet algorithm: a Lorentz invariant generalization of the JADE algorithm. It is found that this generalization amplifies hadronization effects in certain phase space regions in such a way, that hadronization models might become testable in jet physics at the electron--proton collider HERA. Moreover, a method is suggested, which can be used at HERA, in order to determine a region in the phase space, where hadronization effects from the proton remnant are small and where parton jets are particle--like.