辨别胶子喷注和夸克喷注的能量法则研究

A study on the energy rule for the identification of gluon and quark jets

用蒙特卡洛方法研究了e+e-湮灭产生的3-喷注事件,将强子3-喷注按能量排序并通过与部分子层次的3-喷注配对来辨别胶子喷注和夸克喷注.分析了能量法则挑选喷注的纯度;用改进后的能量法则计算了3-喷注事件中的三个喷注的平均多重数,平均横动量随喷注能量的分布以及胶子喷注和夸克喷注的平均多重数之比和平均横动量之比.并与角度法则的相应结果进行了比较.结果显示用改进后的能量法则挑选喷注的方法是可行的.

The three-jet events produced in e^+e^- annihilations at 91.2 GeV are studied using the Monte Carlo method. The hadron jets ordered according to their energies were matched with the three jets at parton level to identify the gluon and quark jets from the events. Energy cut is added in the analysis to improve the purity of selecting jets. The distributions of mean multiplicity and mean transverse momentum of the three jets with the jet's energy and the ratio of <N>_g/<N>_q and <P_t>_g/<P_t>_q are calculated using the improved energy rule. Comparing with the results from the improved angular rule, it is shown that the improved energy rule can be used as an alternative way to identify the gluon and quark jets in experiments.