Fragmentation Properties of Jets Produced in Proton - Collisions at SQRT.S " 1.8 Tev Proton-Anti

Jet fragmentation properties have been studied in collisions of protons and antiprotons at a center-of -mass energy of 1.8 TeV, using the Collider Detector at Fermilab (CDF). The fractional momentum distribution of charged particles within jets is presented and compared with Monte-Carlo predictions. With increasing di-jet invariant mass from 60 to 200 GeV/c^2 the fragmentation is observed to soften as predicted by scale breaking effects in Quantum Chromodynamics (QCD). The charged multiplicity in the jet core is observed to rise with di-jet invariant mass. ftn*This work was supported by the U.S. Department of Energy and Lawrence Berkeley Laboratory under Contract DE-AC03-76SF00098.