Measurement of the Multiplicity of Charged Particles in Jets. Comparisons
to MLLA and Herwig 5.6
Contact Person: Andrey Korytov, Alexei Safonov
Date Blessed: November 19, 1999
CDF Note: CDF5165
Abstract
Updated version of the analys of the inclusive momentum multiplicity of
charged particles in jets. Results are compared to the predictions of Herwig
5.6 and to the calculations carried out in the framework of Modified Leading
Log Approximation. We extract ratio of the multiplicities in gluon and
quark jets, r=1.70+/-0.16, and LPHD parton-to-hadron conversion parameter
K_LPHD= 0.69+/-0.03+/-0.05.
Plots
Plot 1 Inclusive multiplicity of charged
particles within cones 0.168, 0.280 and 0.466 in dijet events. Data errors
are completely dominated by correlated systematic errors. Fit for
possible overall normalization to Herwig v5.6 predictions, yields N=0.89+/-0.05.
The level of the errors does not allow to claim the difference significant.
Herwig predictions were scaled by a factor 0.89 and are shown on the plot
(lines).
Plot 2
Inclusive multiplicity of charged particles within cone 0.466 in dijet
events (empty circles with error bars) compared to MLLA predictions corresponding
to different values of ratio r (incrementing lines) and Herwig v5.6 predictions,
scaled by a factor 0.89, (black diamonds). Data errors are completely dominated
by systematics. Data was fitted for parameters r and K_LPHD.
Plot 3 dN/d(theta) distribution
of charged particles around the jet axis (normalized per jet) in dijet
events at CDF, for three different dijet masses. The Data is compared to
the Monte-Carlo predictions based on Herwig 5.6 convoluted with the simulations
of the detector responce. Uncertainties shown are statistical only. Herwig
predictions were scaled down by a factor 0.89.
Internal CDF Notes: 4886, 4996, 5165