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Phys. Rev. D 65, 052008 (2002) [20 pages]

Subjet multiplicity of gluon and quark jets reconstructed with the k⊥ algorithm in pp̅ collisions
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V. M. Abazov et al. (DØ Collaboration)
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Received 4 September 2001; published 7 February 2002

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 pT of such jets is higher than the ET of matched jets reconstructed with cones of radius R=0.7, by about 5 (8) GeV at pT≈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 sqrt[s]=1800 GeV and 630 GeV is extracted separately for gluons (Mg) and quarks (Mq), and the ratio of average subjet multiplicities in gluon and quark jets is measured as (〈Mg〉-1)/(〈Mq〉-1)=1.84±0.15 (stat)±0.180.22 (syst). This ratio is in agreement with the expectations from the herwig Monte Carlo event generator and a resummation calculation, and with observations in e+e- annihilations, and is close to the naive prediction for the ratio of color charges of CA/CF=9/4=2.25.


©2002 The American Physical Society

URL: http://link.aps.org/abstract/PRD/v65/e052008
DOI: 10.1103/PhysRevD.65.052008
PACS: 13.87.Ce, 12.38.Qk, 14.65.Bt, 14.70.Dj

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