Universality or near-universality of citation distributions was found empirically a decade ago but its theoretical justification has been lacking so far. Here, we systematically study citation distributions for different disciplines in order to characterize this putative universality and to understand it theoretically. Using our calibrated model of citation dynamics, we find microscopic explanation of the universality of citation distributions and explain deviations therefrom. We demonstrate that citation count of the paper is determined, on the one hand, by its fitness -- the attribute which, for most papers, is set at the moment of publication. The fitness distributions for different disciplines are very similar and can be approximated by the log-normal distribution. On another hand, citation dynamics of a paper is related to the mechanism by which the knowledge about it spreads in the scientific community. This viral propagation is non-universal and discipline-specific. Thus, universality of citation distributions traces its origin to the fitness distribution, while deviations from universality are associated with the discipline-specific citation dynamics of papers.

中文翻译：

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引文分布的普遍性及其解释

十年前根据经验发现了引文分布的普遍性或接近普遍性，但迄今为止缺乏其理论依据。在这里，我们系统地研究了不同学科的引文分布，以表征这种假定的普遍性并从理论上理解它。使用我们校准的引文动态模型，我们找到了引文分布普遍性的微观解释，并解释了与之的偏差。我们证明，论文的引用计数一方面取决于其适合度——对于大多数论文而言，该属性是在发表时设置的。不同学科的适应度分布非常相似，可以通过对数正态分布来近似。在另一方面，一篇论文的引用动态与有关它的知识在科学界传播的机制有关。这种病毒传播是非普遍的和特定于学科的。因此，引文分布的普遍性可以追溯到适应度分布，而对普遍性的偏离与论文特定学科的引文动态有关。