流体动力活性物质中响应选择的隐藏超均匀性
Response-Selected Hidden Hyperuniformity in Hydrodynamic Active Matter
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中文总结 AI 辅助
研究流体动力活性物质中超均匀性，引入响应选择超均匀性概念，通过可逆一价流体中局部中性团簇等机制，探讨长波有序及横向力谱特性，揭示微观交换与超均匀流动秩序关系及未屏蔽矩对安静流动状态维持的影响。
中文摘要 AI 辅助
活性物质中的超均匀性通常被视为规定密度或连续场的一种属性。但这种观点忽略了流体动力活性物质的一个基本特征：不可压缩流体对每个微观力的响应并不相同。纵向力被吸收到压力中，而横向力驱动流动。相关问题不仅在于粒子是否均匀排列或总活性是否小，还在于物理响应选择了活性力的哪个部分。本文引入响应选择的超均匀性，其中长波有序是源 - 响应对的一种属性。在没有规定配对的可逆一价流体中，局部中性团簇屏蔽控制横向流动的带符号活性矩扇区，产生在低波数处二次消失的一阶矩谱。局部未屏蔽的矩则产生非零的红外平台。由此产生的横向力谱具有从四阶到六阶缩放的通用交叉，交叉由未屏蔽残余与屏蔽解析贡献的比率设定。完全的配对更新保留这种范式，建立可交换多极继承，而周转通过独立测量的局部缺陷密度调整残余。零残余极限产生严格超均匀的速度波动；任何有限残余都会导致缺陷控制的红外泄漏并设定有限的屏蔽长度。因此微观交换不一定会破坏隐藏的超均匀流动秩序，但罕见的未屏蔽矩决定了安静流动状态能维持多远。
英文摘要
Hyperuniformity in active matter is usually treated as a property of a prescribed density or continuum field. This view misses a basic feature of hydrodynamic active matter: an incompressible fluid does not respond equally to every microscopic force. Longitudinal forcing is absorbed into pressure, whereas transverse forcing drives flow. The relevant question is therefore not only whether particles are uniformly arranged or whether the total activity is small, but which sector of the active forcing is selected by the physical response. Here we introduce response-selected hyperuniformity, in which long-wavelength order is a property of a source-response pair. In a reversible valence-one fluid with no prescribed partners, locally neutral clusters screen the signed active-moment sector that controls transverse flow, producing a first-moment spectrum that vanishes quadratically at low wavenumber. Locally unscreened moments instead generate a nonzero infrared plateau. The resulting transverse-force spectrum has a universal crossover from fourth- to sixth-order scaling, with the crossover set by the ratio of the unscreened residual to the screened analytic contribution. Complete partner renewal preserves this normal form, establishing exchangeable multipole inheritance, while turnover tunes the residual through an independently measured local defect density. The zero-residual limit yields strictly hyperuniform velocity fluctuations; any finite residual causes defect-controlled infrared leakage and sets a finite screening length. Thus microscopic exchange need not destroy hidden hyperuniform flow order, but rare unscreened moments determine how far the quiet-flow regime survives.
