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arXiv 1402.0880hep-phastro-ph.HE
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来自大气中粲产生的中微子

Neutrinos from charm production in the atmosphere

Rikard Enberg

摘要:

大气中微子是由宇宙射线与地球大气层相互作用产生的。在非常高的能量下,来自粲强子的半轻子衰变的贡献,被称为瞬发中微子通量,超过了来自π介子和K介子衰变的常规通量。这是由于粲强子的寿命非常短,因此在衰变之前不会损失能量。这个过程的计算是困难的,因为计算部分子分布函数的Bjorken-x非常小。这是一个量子色动力学还没有被很好理解的区域,大的量子色动力学必须被图解。在如此小的x下,可用的部分子分布函数是未知的,必须进行外推。理论上,小x的结构函数的快速上升最终导致部分子饱和。这篇文章描述了瞬发中微子通量的ERS计算,其中包括在QCD产生的粲夸克截面中的部分子饱和效应。地球资源卫星通量计算被IceCube等机构用作标准基准背景。我们现在正在更新这个计算,以考虑最近LHC的粲截面数据,以及QCD的最新理论发展。在此计算中所涉及的一些问题进行了说明。

英文摘要:

Atmospheric neutrinos are produced in interactions of cosmic rays with Earth's atmosphere. At very high energy, the contribution from semi-leptonic decays of charmed hadrons, known as the prompt neutrino flux, dominates over the conventional flux from pion and kaon decays. This is due to the very short lifetime of the charmed hadrons, which therefore do not lose energy before they decay. The calculation of this process is difficult because the Bjorken-x at which the parton distribution functions are evaluated is very small. This is a region where QCD is not well understood, and large logarithms must be resummed. Available parton distribution functions are not known at such small x and extrapolations must be made. Theoretically, the fast rise of the structure functions for small x ultimately leads to parton saturation. This contribution describes the "ERS" calculation of the prompt neutrino flux, which includes parton saturation effects in the QCD production cross section of charm quarks. The ERS flux calculation is used by e.g. the IceCube collaboration as a standard benchmark background. We are now updating this calculation to take into account the recent LHC data on the charm cross section, as well as recent theoretical developments in QCD. Some of the issues involved in this calculation are described.

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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