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arXiv 1102.3876hep-exphysics.data-an
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B工厂B介子全重构的分层NeuroBayes-based算法

A Hierarchical NeuroBayes-based Algorithm for Full Reconstruction of B Mesons at B Factories

Michael Feindt, Fabian Keller, Michal Kreps, Thomas Kuhr, Sebastian Neubauer, Daniel Zander, Anze Zupanc

摘要:

我们描述了一种新的B介子完全重建算法,该算法是为B工厂KEKB的Belle实验设计的,KEKB是一台非对称e+e对撞机,在运行期间收集了771.6 x 10^6个BBbar对的数据样本。为了最大限度地提高重建的B衰变通道的数量,它利用了一个分层的重建过程和概率演算,而不是经典的选择切割。多变量分析软件包NeuroBayes被广泛用于在尽可能高的效率、鲁棒性和可接受的CPU时间消耗之间保持平衡。总共使用71个神经网络重建了1104个排他性衰变通道。总体而言,我们分别在0.28%或0.18%的BBbar事件中正确重建了一个B+/-或B 0候选。与Belle实验中使用的基于切割的经典重建算法相比,根据所考虑的分析,这是效率的大约2倍的改进。新框架还具有自由选择完全重构样品的所需纯度或效率的能力。如果期望与经典全重构代码相同的纯度~ 25%,则效率仍然高出近2倍。另一方面,如果选择与经典完全重构相似的效率水平,则纯度从约25%上升到近90%。

英文摘要:

We describe a new B-meson full reconstruction algorithm designed for the Belle experiment at the B-factory KEKB, an asymmetric e+e- collider that collected a data sample of 771.6 x 10^6 BBbar pairs during its running time. To maximize the number of reconstructed B decay channels, it utilizes a hierarchical reconstruction procedure and probabilistic calculus instead of classical selection cuts. The multivariate analysis package NeuroBayes was used extensively to hold the balance between highest possible efficiency, robustness and acceptable consumption of CPU time. In total, 1104 exclusive decay channels were reconstructed, employing 71 neural networks altogether. Overall, we correctly reconstruct one B+/- or B0 candidate in 0.28% or 0.18% of the BBbar events, respectively. Compared to the cut-based classical reconstruction algorithm used at the Belle experiment, this is an improvement in efficiency by roughly a factor of 2, depending on the analysis considered. The new framework also features the ability to choose the desired purity or efficiency of the fully reconstructed sample freely. If the same purity as for the classical full reconstruction code is desired ~25%, the efficiency is still larger by nearly a factor of 2. If, on the other hand, the efficiency is chosen at a similar level as the classical full reconstruction, the purity rises from ~25% to nearly 90%.

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。

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