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A Monte Carlo Study on Cone-Angle Property of the Quark- and Gluon-Jets Identified by b-Tag Method |
| CHEN Gang1,3; LIU Lian-Shou2 |
| 1Department of Physics, China University of Geosciences, Wuhan 430074
2Institute of Particle, Huazhong Normal University, Wuhan 430079
3Department of Physics, Yangtze University, Jingzhou 434020 |
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| Cite this article: |
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CHEN Gang, LIU Lian-Shou 2005 Chin. Phys. Lett. 22 839-842 |
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Abstract Quark and gluon jets are studied in three-jet events generated by Jetset 7.4 and Herwig 5.9 at √s = 91.2GeV. The quark jets are identified by b-tag tracing, and the remaining jet is then defined as the gluon jet. A new physical variable, i.e. the cone-angle, which is able to describe the geometrical characteristic of the jet, is defined. It turns out that the cone-angle distribution of the gluon jet is wider than its mother quark jet, i.e. the gluon jet is ``fatter''. As the multiplicity increases, the cone-angle distribution of the quark jet has an upward-going trend, i.e. a positive correlation is present. The cone-angle of the gluon and quark jet versus their transverse momentum develop a valley. The mean cone-angles of both the gluon jet and the quark jet are negatively correlated with the transverse momentum for pt < 3GeV/c, but are positively correlated for pt > 3GeV/c. The mean cone-angles of the gluon and quark jets are well separated, showing that they can be utilized in the identification of the two kinds of jets.
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| Keywords:
13.87.Fh
13.66.Bc
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Published: 01 April 2005
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| PACS: |
13.87.Fh
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(Fragmentation into hadrons)
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13.66.Bc
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(Hadron production in e?e+ interactions)
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