arXiv 1504.060192015-04hep-ph

在HERA处片段化对$J/ψ$光产生的贡献

Fragmentation contributions to $J/ψ$ photoproduction at HERA

Geoffrey T. Bodwin, Hee Sok Chung, U-Rae Kim, Jungil Lee

备注：: 16 pages, 6 figures, minor revisions, version published in Phys. Rev. D
发表信息：: Phys. Rev. D 92, 074042 (2015)
DOI：: 10.1103/PhysRevD.92.074042

摘要：

利用非相对论QCD因子分解方法，计算了DESY HERA的$J/ψ$光生的主导功率碎裂修正。我们的计算包括通过$α_s^3$阶的部分子产生截面，通过$α_s^2$阶的碎裂函数，以及$α_s$中所有阶的横动量除以粲夸克质量的导矢。我们发现，领先的功率碎片化校正，除了那些包括通过下一个到领先的顺序在$α_s$，是小的相对于固定顺序的贡献，通过下一个到领先的顺序在$α_s$。因此，一个重要的差异仍然存在之间的实验测量的$J/ψ$光生截面和预测，利用非相对论QCD长距离矩阵元素提取的$J/ψ$ hadroproduction截面和偏振数据。

英文摘要：

We compute leading-power fragmentation corrections to $J/ψ$ photoproduction at DESY HERA, making use of the nonrelativistic QCD factorization approach. Our calculations include parton production cross sections through order $α_s^3$, fragmentation functions though order $α_s^2$, and leading logarithms of the transverse momentum divided by the charm-quark mass to all orders in $α_s$. We find that the leading-power fragmentation corrections, beyond those that are included through next-to-leading order in $α_s$, are small relative to the fixed-order contributions through next-to-leading order in $α_s$. Consequently, an important discrepancy remains between the experimental measurements of the $J/ψ$ photoproduction cross section and predictions that make use of nonrelativistic-QCD long-distance matrix elements that are extracted from the $J/ψ$ hadroproduction cross-section and polarization data.

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英文摘要：

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