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arXiv 1503.08439hep-ph
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Tevatron和LHC上$Υ$产生和极化的最新研究

An Updated Study for $Υ$ Production and Polarization at the Tevatron and LHC

Yu Feng, Bin Gong, Lu-Ping Wan, Jian-Xiong Wang

摘要:

采用非相对论QCD因子化方案,结合最近的$χ_b(3P)$测量结果,我们对$Υ(1S,2S,3S)$强子产生的产额和极化以及$χ_b(mP)$在$Υ(nS)$产生中的反馈分数进行了最新的研究.在拟合过程中,分别采用了三种不同的$χ_b(mP)$格式,并分别选择了不同的$χ_b(mP)$馈下比和NRQCD分解尺度。这些结果可以很好地解释产率的测量结果。现在,通过考虑$χ_b(3P)$的馈下贡献,解决了$Υ(3S)$的偏振难题。CMS的$σ[χ_{b2}(1P)]/σ[χ_{b1}(1P)]$测量值的比率也可以在我们的预测中重现。不同方案的计算结果差别不大,但拟合出的长距离色八重矩阵元差别较大。当这些数值应用于其他实验中时,如$ee,~ep$对撞机中,可能会带来很大的不确定性。

英文摘要:

Following the nonrelativistic QCD factorization scheme, by taking latest available measurement on $χ_b(3P)$ into consideration, we present an updated study on the yield and polarization of $Υ(1S,2S,3S)$ hadroproduction, and the fractions of $χ_b(mP)$ feed-down in $Υ(nS)$ production at QCD next-to-leading order. In the fitting, three schemes are applied with different choice of $χ_b(mP)$ feed-down ratios and NRQCD factorization scale. The results can explain the measurements on yield very well as in our previous work. The polarization puzzle to $Υ(3S)$ is now solved by considering the $χ_b(3P)$ feed-down contributions. The ratio of $σ[χ_{b2}(1P)]/σ[χ_{b1}(1P)]$ measurements from CMS can also be reproduced in our prediction. Among the different schemes, the results show little difference, but there are sizeable difference for the fitted long-distance color-octet matrix elements. It may bring large uncertainty when the values are applied in other experiments such as in $ee,~ep$ colliders.

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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