We report the first model independent measurement of charged
particle multiplicities in quark and gluon jets, N_q and N_g, produced at
the Tevatron in p anti-p collisions with center-of-mass energy 1.8 TeV and
recorded by the Collider Detector at Fermilab. The measurements are made
for jets with average energies 41 and 53 GeV by counting charged particle
tracks in cones with opening angle of theta_c = 0.28, 0.36, and 0.47 rad
around the jet axis. The corresponding jet hardness Q = E_jet theta_c
varies in the range from 12 GeV to 25 GeV. At Q = 19 GeV, the ratio of
multiplicities r = N_g/N_q is found to be 1.64 +/- 0.17, where statistical
and systematic uncertainties are added in quadrature. The results are in
agreement with re-summed perturbative QCD calculations.
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Updated: Friday, 2005 May 20 14:49:50 CDT automatically from input from Carol Picciolo