Experimental properties of gluon and quark jets from a point source
Experimental properties of gluon and quark jets from a point source
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DOI：
10.1007/s100520050628
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发表时间：
1999-11-01
影响因子：
4.4
通讯作者：
Zer-Zion, D
中科院分区：
文献类型：
--
作者：
Abbiendi, G;Ackerstaff, K;Zer-Zion, D
胶子喷流在强子Z(0)衰变中被识别，即与包含两个标记的夸克喷注的半球相对的半球中的所有粒子。以这种方式定义的胶子喷注等同于从彩色单重态点源产生的胶子喷注，因此与大多数理论计算所采用的定义相对应。在分析的单独阶段，我们以一种与计算相对应的方式选择夸克喷注，作为味标记轻夸克(UDS)事件的半球中的粒子。我们给出了这些胶子和夸克喷注中带电粒子的快度、标度能量、动量的对数和横向动量相对于喷射轴的分布。我们还研究了在有限的快度区间内喷流的带电粒子多重数分布。对于大Pr的软粒子，我们观察到胶子喷注和夸克喷注的带电粒子多重数比为2.291+/-0.09(统计)+/-0.15(系统)，这与该比应近似等于QCD颜色因子之比C-A/C-F=2.25时的预测一致。用于定义软粒子和大p(T)的间隔p<；4GeV/c和0.8<；p(T)<；3.0GeV/c，是由Herwig蒙特卡罗多强子事件产生器的预测推动的。此外，我们的胶子喷注数据允许对称为颜色重联的非领先QCD项的现象进行灵敏的测试。我们测试了Ariadne蒙特卡罗多强子事件产生器中实现的颜色重联模型，发现它不符合我们的数据。
Gluon jets are identified in hadronic Z(0) decays as all the particles in a hemisphere opposite to a hemisphere containing two tagged quark jets. Gluon jets defined in this manner are equivalent to gluon jets produced from a color singlet point source and thus correspond to the definition employed for most theoretical calculations. In a separate stage of the analysis, we select quark jets in a manner to correspond to calculations, as the particles in hemispheres of flavor tagged light quark (uds) events. We present the distributions of rapidity, scaled energy, the logarithm of the momentum, and transverse momentum with respect to the jet axes, for charged particles in these gluon and quark jets. We also examine the charged particle multiplicity distributions of the jets in restricted intervals of rapidity. For soft particles at large pr, we observe the charged particle multiplicity ratio of gluon to quark jets to be 2.291+/-0.09 (stat.)+/-0.15 (syst.), in agreement with the prediction that this ratio should approximately equal the ratio of QCD color factors, C-A/C-F = 2.25. The intervals used to define soft particles and large p(T) for this result, p < 4 GeV/c and 0.8 < p(T) < 3.0 GeV/c, are motivated by the predictions of the Herwig Monte Carlo multihadronic event generator. Additionally, our gluon jet data allow a sensitive test of the phenomenon of non-leading QCD terms known as color reconnection. We test the model of color reconnection implemented in the Ariadne Monte Carlo multihadronic event generator and find it to be disfavored by our data.