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arXiv 2602.00374cond-mat.stat-mechcond-mat.dis-nnnlin.AO
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记忆效应支配超越普遍类别的无标度动力学

Memory effects govern scale-free dynamics beyond universality classes

Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS(物质之光研究所,UMR5306里昂第一大学-CNRS)

K. Duplat, A. Douin, O. Ramos

AI总结:

研究揭示了记忆效应在超越普遍类别的无标度动力学中的作用,通过模拟显示临界行为向准临界动力学的转变,指数值受耗散影响。

摘要:

无标度崩塌--所有大小的事件遵循幂律分布--被认为是临界性的。在四维以上,平均场解具有稳健的3/2大小指数描述动力学。在二维和三维中,空间约束导致较小但稳健的指数值,由普遍类决定。然而,地震数据和实验往往显示指数值大于3/2,挑战了基于临界行为的理论论点。通过在经典OFC地震模型中的广泛模拟,我们在这里展示了从理论预期行为的稳健指数值向具有大于3/2指数值的准临界动力学的转变,这些指数值取决于耗散。第一临界区域表现出本质上无记忆的行为,而过渡和第二区域则由记忆效应驱动,这些记忆效应由崩塌在先前事件留下的痕迹上生长引起,由于耗散机制。系统在距离临界点d_cp的距离处,考虑d_cp的幂律分布,通过易感性测量验证,捕捉了这一转变。该框架为临界和准临界行为提供了统一的描述,从而为自然界中观察到的完整无标度动力学光谱提供了描述。

英文摘要:

Scale-invariant avalanches -- with events of all sizes following power-law distributions -- are considered critical. Above the upper critical dimension of four, the mean-field solution with a robust $3/2$ size exponent describes the dynamics. In two and three dimensions, spatial constraints yield smaller yet robust exponent values governed by universality classes. However, both earthquake data and experiments often show exponent values larger than $3/2$, challenging those theoretical arguments based on critical behavior. Through extensive simulations in the classical OFC earthquake model, here we show a clear transition from the theoretical expected behavior of a robust exponent value, to a regime of quasi-critical dynamics with larger than $3/2$ exponents that depend on dissipation. While the first critical regime exhibits an inherently memoryless behavior, both the transition and the second regime are driven by memory effects provoked by the growth of avalanches over the traces left by previous events, due to dissipative mechanisms. The system hovers at a distance $d_{cp}$ from the critical point, and accounting for a power-law distribution of $d_{cp}$, validated by susceptibility measurements, captures the transition. This framework provides a unified description of both critical and quasi-critical behavior, and thus of the full spectrum of scale-free dynamics observed in nature.

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