Jet Energy Density in Hadron-Hadron Collisions at High Energies

The average particle multiplicity density dN/dη is the dynamical quantity which reflects some regularities of particle production in low- p T range. The quantity is an important ingredient of z -scaling. Experimental results on charged particle density are available for pp , pA and AA collisions while experimental properties of the jet density are still an open question. The goal of this work is to find the variable which will reflect the main features of the jet production in low transverse energy range and play the role of the scale factor for the scaling function ψ ( z ) and variable z in data z -presentation. The appropriate candidate is the variable we called ”scaled jet energy density”. Scaled jet energy density is the probability to have a jet with defined E T in defined x T and pseudorapidity regions. The PYTHIA6.2 Monte Carlo generator is used for calculation of scaled jet energy density in proton-proton collisions over a high energy range ( √ s = 200 − 14000 GeV) and at η = 0. The properties of the new variable are discussed and sensitivity to ”physical scenarios” applied in the standard Monte Carlo generator is noted. The results of scaled jet energy density at LHC energies are presented and compared with predictions based on z -scaling.