The odd-even staggering (OES) in nuclear binding energies is a well-known fact. A rather similar effect can be found in other finite fermion systems. For instance, ultra small metallic grains and metal clusters. The staggering in nuclei and grains is attributed primarily to pairing correlations. In clusters, it is originated by the Jahn–Teller effect [Phys. Rev. Lett. 81, 3599 (1998)]. Here, we work with a simple, Lipkin-like, exactly solvable two-level fermion model. A statistical mechanics’ treatment of it shows that OES effects also emerge here, as revealed by theoretical tools connected with the so-called statistical complexity.

中文翻译：

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少数费米子系统中的统计奇偶交错

核结合能的奇偶交错 (OES) 是众所周知的事实。在其他有限费米子系统中可以找到相当相似的效果。例如，超小的金属颗粒和金属簇。原子核和晶粒的惊人变化主要归因于配对相关性。在集群中，它起源于 Jahn-Teller 效应 [物理。牧师莱特。 81, 3599 (1998)]。在这里，我们使用了一个简单的、类似 Lipkin 的、完全可解的两能级费米子模型。统计力学对其的处理表明，OES 效应也出现在这里，正如与所谓的统计复杂性相关的理论工具所揭示的那样。