Subjet multiplicity of gluon and quark jets reconstructed with the k _┴ algorithm in pp̅ collisions

Authors

• V. M. Abazov, Joint Institute for Nuclear Research, Dubna, Russia
• Gregory R. Snow, University of Nebraska-LincolnFollow
• D0 Collaboration

Document Type

Article

Date of this Version

2-6-2002

Comments

Published by American Physical Society. Phys. Rev. D 65, 052008 (2002). http://prd.aps.org. Copyright © 2002 American Physical Society. Used by permission.

Abstract

The DØ 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 _┴) of energy clusters. Using the standard value D=1.0 of the jet-separation parameter in the k _┴ 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 ≈'90 (240) GeV. To examine internal jet structure, the k _┴ algorithm is applied within D=0.5 jets to resolve any subjets. The multiplicity of subjets in jet samples at √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±0.15 (stat) ±_-0.18^+0.22 (syst). This ratio is in agreement with the expectations from the HERWIG Monte Carlo event generator and a resummation calculation, and with observations in e1e2 annihilations, and is close to the naive prediction for the ratio of color charges of C_A /C_F=9/4 =2.25.