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北美退伍军人节(Veterans Day),12 日无更新
arXiv 0811.3662hep-phnucl-th
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大横动量下的低质量轻子对产生

Low-mass lepton pair production at large transverse momentum

Zhong-Bo Kang, Jian-Wei Qiu, Werner Vogelsang

摘要:

利用微扰QCD因式分解方法研究了强子散射中产生的低质量轻子对的横动量分布。我们认为,分布在大的横向动量,$Q_T \gg Q$,与对的不变质量$Q$低至$Q \sim Λ_{\mathrm{QCD}}$,可以系统地分解成通用的部分子到轻子对碎裂功能,部分子分布,和微扰计算的部分子硬部分评估在短距离尺度$\sim {\cal O}(1/Q_T)$。我们介绍了一个模型的输入轻子对碎裂函数在$μ_0\sim 1$ GeV的规模,然后微扰演化到相关的RHIC的规模。利用演化的碎裂函数,我们计算了RHIC强子-强子、强子-核和核-核碰撞中的横动量分布。我们还讨论了低质量轻子对的横动量分布对胶子分布的敏感性。

英文摘要:

We study the transverse momentum distribution of low-mass lepton pairs produced in hadronic scattering, using the perturbative QCD factorization approach. We argue that the distribution at large transverse momentum, $Q_T \gg Q$, with the pair's invariant mass $Q$ as low as $Q \sim Λ_{\mathrm{QCD}}$, can be systematically factorized into universal parton-to-lepton pair fragmentation functions, parton distributions, and perturbatively calculable partonic hard parts evaluated at a short distance scale $\sim {\cal O}(1/Q_T)$. We introduce a model for the input lepton pair fragmentation functions at a scale $μ_0\sim 1$ GeV, which are then evolved perturbatively to scales relevant at RHIC. Using the evolved fragmentation functions, we calculate the transverse momentum distributions in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions at RHIC. We also discuss the sensitivity of the transverse momentum distribution of low-mass lepton pairs to the gluon distribution.

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