/ Experiment-HEP hep-ex/0108054

Subjet multiplicity of gluon and quark jets reconstructed with the k-perpendicular algorithm in p anti-p collisions

Abazov, V.M. ; Abbott, B. ; Abdesselam, A. ; Abolins, M. ; Abramov, V. ; Acharya, Bannanje Sripath ; Adams, D.L. ; Adams, M. ; Ahmed, S.N. ; Alexeev, G.D. ; Alton, A. ; Alves, G.A. ; Amos, Norman A. ; Anderson, E.W. ; Arnoud, Y. ; Avila, C. ; Baarmand, M.M. ; Babintsev, V.V. ; Babukhadia, Levan R. ; Bacon, T.C. ; Baden, A. ; Baldin, B. ; Balm, P.W. ; Banerjee, S. ; Barberis, E.

Published in: Phys.Rev.
Year: 2002
Vol.: D65
Page No: 052008
Pages: 43

Abstract: The D0 Collaboration has studied for the first time the properties of hadron-collider jets reconstructed with a successive-combination algorithm based on relative transverse momenta ($k_{\perp}$) of energy clusters. Using the standard value D = 1.0 of the jet-separation parameter in the $k_{\perp}$ algorithm, we find that the $p_T$ of such jets is higher than the $E_T$ of matched jets reconstructed with cones of radius R = 0.7, by about 5 (8) GeV at $p_T \approx 90$ (240) GeV. To examine internal jet structure, the $k_{\perp}$ algorithm is applied within D = 0.5 jets to resolve any subjets. The multiplicity of subjets in jet samples at $\sqrt{s} = 1800$ GeV and 630 GeV is extracted separately for gluons ($M_g$) and quarks ($M_q$), and the ratio of average subjet multiplicities in gluon and quark jets is measured as $(M_{g} - 1) / (M_{q} - 1) = 1.84 \pm 0.15 (stat.) \pm ^{0.22}_{0.18} (sys.)$. This ratio is in agreement with the expectations from the HERWIG Monte Carlo event generator and a resummation calculation, and with observations in $e^+e^-$ annihilations, and is close to the naive prediction for the ratio of color charges of $C_A/C_F = 9/4 = 2.25$.

Keyword(s): D0

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