Contact Person: Andrey Korytov, Alexei Safonov
Date Blessed: December 3, 1999
CDF Note: CDF5182
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.
Plot 1 Inclusive momentum distribution of charged particles in dijet events within restricted cone 0.47 fitted with MLLA limiting spectrum. 9 dijet mass bins with Mjj=80-630 GeV. Numerical values for fitted parameters K and Qeff are in Table 1. Events analyzed are a mixture of quark and gluon jets, therefore K is not exactly LPHD parton-to-hadron conversion parameter KLPHD.
Plot 2 dN/dlog(p) distribution of particles in di-jet events for 4 different dijet masses. Only particles within restricted cone 0.47 are included. The plot shows that soft part of the spectrum is practically independent of the energy. This is direct consequence of color-coherent fragmentation.
Plot 3 Inclusive momentum distribution of charged particles within restricted cones 0.466 in dijet events fitted with MLLA limiting spectrum. Dijet mass Mjj=378 GeV.
Plot 4 Peak position of the inclusive momentum distribution as a function of Mjj sin(q) for all avaiable dijet mass-restricted cone-size combinations. Data errors are completely dominated by systematics. CDF Data is fitted for MLLA parameter Qeff . For illustration, the data from ee and ep experiments is shown on the same plot. Top dashed line corresponds to theoretical expectations for the case of color-incoherent fragmentation, the bottom line is the Leading Log result.
Plot
5 Plot of the parameter K for the restricted cone 0.47 as a
function of the gluon jet fraction in the data. Uncertainties in
K are dominated by systematics and are strongly correlated. The
data is fitted for the LPHD parton-to-hadron conversion parameter
KLPHD and r, the ratio of hadron multiplicities in gluon and
quark jets.
Internal CDF Notes: 4886, 4996, 5041, 5182