Title: Liquid-Gas Criticality of Hyperuniform Fluids Show Chinese title

Title: 超均匀流体的液-气临界性

Abstract: In statistical physics, it is well established that the liquid-gas (LG) phase transition with divergent critical fluctuations belongs to the Ising universality class. Whether non-equilibrium effects can alter this universal behavior remains a fundamental open question. Here, we theoretically investigate LG criticality in a hyperuniform (HU) fluid of active spinners, where phase separation is driven by dissipative collisions. Strikingly, at the critical point the HU fluid displays normal Gaussian density fluctuations rather than the expected divergence, while the compressibility still diverges. The system is thus calm yet highly susceptible, in fundamental violation of the conventional fluctuation-dissipation theorem. Consistently, we observe anomalous zero-range correlation functions coexisting with quasi-long-range response functions. Based on a generalized model B and renormalization-group analysis, we show that hyperuniformity reduces the upper critical dimension from $d_c = 4$ to $d_c = 2$, and the system exhibits anomalous finite-size scaling in density fluctuations, energy fluctuations, and the Binder cumulant. Furthermore, the HU fluid undergoes non-classical spinodal decomposition, where the decomposition time diverges but the characteristic length scale remains finite as criticality is approached. The origin of these anomalies lies in the center-of-mass-conserving dynamics of the spinners, which endows the system with a scale-dependent effective temperature, $T_{\rm eff} \propto q^2$, underlying a generalized fluctuation-dissipation relationship. These findings establish a striking exception to classical paradigms of critical phenomena and illustrate how non-equilibrium forces can fundamentally reshape universality classes. Show Chinese abstract

Abstract: 在统计物理中，液气（LG）相变伴随发散的临界涨落属于伊辛普适类，这是已确立的。非平衡效应能否改变这种普适行为仍然是一个基本的开放问题。在这里，我们理论研究了活性旋转向量的超均匀（HU）流体中的LG临界性，其中相分离是由耗散碰撞驱动的。显著的是，在临界点，HU流体表现出正常的高斯密度涨落，而不是预期的发散，而压缩率仍然发散。因此，系统是平静的但高度敏感的，这根本违反了传统的涨落-耗散定理。一致地，我们观察到异常的零范围关联函数与准长程响应函数共存。基于广义模型B和重整化群分析，我们表明超均匀性将上临界维数从$d_c = 4$降低到$d_c = 2$，并且系统在密度涨落、能量涨落和Binder峰度中表现出异常的有限尺寸标度。此外，HU流体经历非经典的旋转变分解，其中分解时间发散，但作为临界性接近时特征长度尺度保持有限。这些异常的根源在于旋转向量的质心守恒动力学，这赋予系统一个与尺度相关的有效温度$T_{\rm eff} \propto q^2$，这是广义涨落-耗散关系的基础。这些发现确立了经典临界现象范式的显著例外，并说明了非平衡力如何从根本上重塑普适类。