用软轻子标记排除带-4/3电荷的奇异顶夸克
Exclusion of an Exotic Top Quark with -4/3 Electric Charge Using Soft Lepton Tagging
摘要：
我们利用积分光度为2.7~fb的$^{-1}$的$\ppbar$碰撞测量了顶夸克的电荷。我们重建了轻子+喷流末态的$\ttbar$事件，并利用运动学信息来确定哪一个$b$ -喷流与轻子衰变或强子衰变的$t$ -夸克有关。软轻子示踪剂用于确定$b$ -jet风味。连同$W$玻色子衰变轻子的电荷，这些信息允许重建顶夸克的电荷。在具有$2.4\pm0.8$预期背景事件的45个重建事件中，29个重建为具有标准模型$+$ 2/3电荷的$\ttbar$，而16个重建为具有外来$-4/3$电荷的$\ttbar$。这与标准模型一致，在95%的置信水平上排除了外来情景。这是最强的排斥外来电荷的情况下，第一次使用软轻子为此目的。
英文摘要：
We present a measurement of the electric charge of the top quark using $\ppbar$ collisions corresponding to an integrated luminosity of 2.7~fb$^{-1}$ at the CDF II detector. We reconstruct $\ttbar$ events in the lepton+jets final state and use kinematic information to determine which $b$-jet is associated with the leptonically- or hadronically-decaying $t$-quark. Soft lepton taggers are used to determine the $b$-jet flavor. Along with the charge of the $W$ boson decay lepton, this information permits the reconstruction of the top quark's electric charge. Out of 45 reconstructed events with $2.4\pm0.8$ expected background events, 29 are reconstructed as $\ttbar$ with the standard model $+$2/3 charge, whereas 16 are reconstructed as $\ttbar$ with an exotic $-4/3$ charge. This is consistent with the standard model and excludes the exotic scenario at 95\% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
