A comparison of b and uds quark jets to gluon jets
A comparison of b and uds quark jets to gluon jets
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DOI：
10.1007/s002880050059
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发表时间：
1996-02-01
期刊：
影响因子：
--
通讯作者：
Zacek, V
中科院分区：
文献类型：
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作者：
Alexander, G;Allison, J;Zacek, V
对称三射流事件选自强子 Z(0) 衰变，使得两个较低能量射流艺术：每个产生的角度相对于最高能量射流约 150 度。在某些情况下，在两个较低能量射流之一中重建移位的次顶点，这允许通过反标记将另一个较低能量射流识别为胶子射流。在其他情况下，使用次要顶点或轨道冲击参数和动量信息将最高能量射流标记为 b 射流或轻夸克 (uds) 射流。将最高能量射流中带有标签的事件中的两个较低能量射流与反标记胶子射流进行比较，可以直接比较 b、uds 和胶子射流，它们是在相同条件下以约 24 GeV 的相同能量产生的。我们观察到 b 射流和胶子射流具有相似的特性，这是通过射流方向周围粒子能量的角分布和破碎函数来测量的。相比之下，胶子射流被发现比 uds 射流明显更宽，并且具有明显更软的破碎功能。对于 y(cut)=0.02 的 k（垂直于）射流探测器，我们发现 [n(ch.)](gluon)/[n(ch.)](b 夸克) = 1.089 +/- 0.024 (stat.) +/- 0.024 (syst.)[n(ch.)](gluon)/[n(ch.)](uds 夸克) = 1.390 +/- 0.038（统计）+/- 0.032（系统）作为胶子射流中平均带电粒子多重性与 b 和 uds 射流相比的比率。还使用锥形射流探测器报告结果。
Symmetric three-jet events are selected from hadronic Z(0) decays such that the two lower energy jets art: each produced at an angle of about 150 degrees with respect to the highest energy jet. In some cases, a displaced secondary vertex is reconstructed in one of the two lower energy jets, which permits the other lower energy jet to be identified as a gluon jet through anti-tagging. In other cases, the highest energy jet is tagged as a b jet or as a light quark (uds) jet using secondary vertex or track impact parameter and momentum information. Comparing the two lower energy jets of the events with a tag in the highest energy jet to the anti-tagged gluon jets yields a direct comparison of b, uds and gluon jets, which are produced with the same energy of about 24 GeV and under the same conditions. We observe b jets and gluon jets to have similar properties as measured by the angular distribution of particle energy around the jet directions and by the fragmentation functions. In contrast, gluon jets are found to be significantly broader and to have a markedly softer fragmentation function than uds jets. For the k(perpendicular to) jet finder with y(cut)=0.02, we find[n(ch.)](gluon)/[n(ch.)](b quark) = 1.089 +/- 0.024 (stat.) +/- 0.024 (syst.)[n(ch.)](gluon)/[n(ch.)](uds quark) = 1.390 +/- 0.038 (stat.) +/- 0.032 (syst.)as the ratios of the mean charged particle multiplicity in the gluon jets compared to the b and uds jets. Results are also reported using the cone jet finder.