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
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
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.
CHEN Gang; LIU Lian-Shou. A Monte Carlo Study on Cone-Angle Property of the Quark- and Gluon-Jets Identified by b-Tag Method[J]. 中国物理快报, 2005, 22(4): 839-842.
CHEN Gang, LIU Lian-Shou. A Monte Carlo Study on Cone-Angle Property of the Quark- and Gluon-Jets Identified by b-Tag Method. Chin. Phys. Lett., 2005, 22(4): 839-842.
2005, Vol. 22 
