本文将 K$ϕ$MP$ϕ$ST 预平衡形式体系扩展至守恒电荷，在弛豫时间近似下计算非平衡 Green 函数，并结合 ICCING 初始条件展示其对电荷几何的改变及适用碰撞范围。
摘要：
重离子碰撞可以通过相对论黏性流体力学得到很好的描述，但由于初始状态可能从远离平衡的状态开始，流体力学何时适用仍存在问题。因此，人们采用预平衡演化阶段来弥合初始状态与流体力学之间的差距。K$ϕ$MP$ϕ$ST 就是这样一种预平衡模型，它通过将能量-动量张量分解为背景和围绕该背景的涨落来传播能量-动量张量，而背景的演化由 Green 函数刻画。我们将这一形式体系扩展到包含守恒电荷，并在弛豫时间近似下计算相应的非平衡 Green 函数。ICCING 算法通过抽样 $g \ ightarrow q\ar{q}$ 分裂概率来初始化初始状态中的守恒电荷，因此非常适合实现用于电荷传播的 Green 函数。我们表明，该方法会改变初始状态的电荷几何结构，并适用于中心到中度中心碰撞。
英文摘要：
Heavy-ion collisions can be well described through relativistic viscous hydrodynamics, but questions still remain when hydrodynamics is applicable because the initial state may begin very far-from-equilibrium. Thus, a pre-equilibrium evolution phase is used to bridge the gap between the initial state and hydrodynamics. K$ϕ$MP$ϕ$ST is one such pre-equilibrium model that propagates the energy-momentum tensor by decomposing it into the background and fluctuations around that background, whose evolution is captured by Green's functions. We extend this formalism to include conserved charges and calculate the corresponding non-equilibrium Green's functions in the relaxation time approximation. The ICCING algorithm initializes conserved charges in the initial state by sampling $g \rightarrow q\bar{q}$ splitting probabilities and is, thus, perfectly positioned to implement Green's functions for charge propagation. We show that this method alters the initial state charge geometries and is applicable in central to mid-central collisions.
At top collider energies where baryon stopping is negligible, the initial state of heavy ion collisions is overall charge neutral and predominantly composed of gluons. Nevertheless, there can also be significant local fluctuations of the baryon number, strangeness, and electric charge densities about zero, perturbatively corresponding to the production of quark/antiquark pairs. These previously ignored local charge fluctuations can permit the study of charge diffusion in the quark-gluon plasma (QGP), even at top collider energies. In this paper we present a new model denoted ICCING (Initial Co…
While it is well known that there is a significant amount of conserved charges in the initial state of nuclear collisions, the production of these due to gluon splitting has yet to be thoroughly investigated. The ICCING (Initial Conserved Charges in Nuclear Geometry) algorithm reconstructs these quark distributions, providing conserved strange, baryon, and electric charges, by sampling a given model for the $g \rightarrow q\bar{q}$ splitting function over the initial energy density, which is valid at top collider energies, even when $μ_B=0$. The ICCING algorithm includes fluctuations in the gl…
We initialize the Quantum Chromodynamic conserved charges of baryon number, strangeness, and electric charge arising from gluon splitting into quark-antiquark pairs for the initial conditions of relativistic heavy-ion collisions. A new Monte Carlo procedure that can sample from a generic energy density profile is presented, called Initial Conserved Charges in Nuclear Geometry (ICCING), based on quark and gluon multiplicities derived within the color glass condensate (CGC) effective theory. We find that while baryon number and electric charge have nearly identical geometries to the energy densi…
Dissipative processes in relativistic fluids are known to be important in the analyses of the hot QCD matter created in high-energy heavy-ion collisions. In this work, I consider dissipative corrections to energy and conserved charge densities, which are conventionally assumed to be vanishing but could be finite. Causal dissipative hydrodynamics is formulated in the presence of those dissipative currents. The relation between hydrodynamic stability and transport coefficients is discussed. I then study their phenomenological consequences on the observables of heavy-ion collisions in numerical s…
We investigate the time evolution of higher order cumulants of conserved charges in a volume with the diffusion master equation. Applying the result to the diffusion of non-Gaussian fluctuations in the hadronic stage of relativistic heavy ion collisions, we show that the fourth-order cumulant of net-electric charge at LHC energy is suppressed compared with the recently observed second-order cumulant at ALICE, if the higher order cumulants at hadronization are suppressed compared with their values in the hadron phase in equilibrium. The significance of the experimental information on the rapidi…
The thermodynamics of a first-order chiral phase transition is considered in the presence of spinodal phase separation using the Nambu-Jona-Lasinio model in the mean field approximation. We focus on the behavior of conserved charge fluctuations. We show that in non-equilibrium the specific heat and charge susceptibilities diverge as the system crosses the isothermal spinodal lines.
We show that in the presence of spinodal instabilities which develop at a first order phase transition, the fluctuations of conserved charges can be as strong as those at the critical end point (CEP). In particular, the net baryon number susceptibility diverges as the system crosses the isothermal spinodal lines. This indicates that charge density fluctuations can be used not only to probe the CEP but also the non--equilibrium first order chiral phase transition in heavy ion collisions.
For hadron production in high energy collisions, causality requirements lead to the counterpart of the cosmological horizon problem: the production occurs in a number of causally disconnected regions of finite space-time size. As a result, globally conserved quantum numbers (charge, strangeness, baryon number) must be conserved locally in spatially restricted correlation clusters. This provides a theoretical basis for the observed suppression of strangeness production in elementary interactions (pp, e^+e^-). In contrast, the space-time superposition of many collisions in heavy ion interactions…
Diffusion of multiple conserved charges from entropy production
Indian Institute of Science Education and Research Berhampur（印度科学教育研究所布巴内斯瓦尔分校）；Birla Institute of Technology and Science Pilani（比拉理工学院皮拉尼校区）；National Institute of Science Education and Research（国家科学教育与研究学院）
Self-similar inverse cascade from generalized symmetries
Institute of Systems and Information Engineering, University of Tsukuba（筑波大学系统信息工程学院）；Department of Physics, Osaka University（大阪大学物理学系）；School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences (HIAS-UCAS)（中国科学院大学杭州高等研究院基础物理与数学学院）；International Centre for Theoretical Physics Asia-Pacific (ICTP-AP)（亚太理论物理中心）；Research Center for the Early Universe, The University of Tokyo（东京大学宇宙早期研究数据中心）；Department of Physics, Keio University（庆应义塾大学物理学系）；Department of Physics & Research and Education Center for Natural Sciences, Keio University（庆应义塾大学物理学系及自然科学研究与教育中心）
Causality and Stability of First-Order Relativistic Spin Hydrodynamics with Conserved Charges
College of Mathematics and Physics, China Three Gorges University（三峡大学数学与物理学院）；Center for Astronomy and Space Sciences and Institute of Modern Physics, China Three Gorges University（三峡大学天文与空间科学中心及现代物理研究所）；Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University（华中师范大学夸克与轻子物理教育部重点实验室及粒子物理研究所）
The effective low-energy late-time description of many body systems near thermal equilibrium provided by classical hydrodynamics in terms of dissipative transport phenomena receives important corrections once the effects of stochastic fluctuations are taken into account. One such physical effect is the occurrence of long-time power law tails in correlation functions of conserved currents. In the hydrodynamic regime $\vec{k} \rightarrow 0$ this amounts to non-analytic dependence of the correlation functions on the frequency $ω$. In this article, we consider a relativistic fluid with a conserved…
Boltzmann's principle S(E,N,V...)=ln W(E,N,V...) allows the interpretation of Statistical Mechanics of a closed system as Pseudo-Riemannian geometry in the space of the conserved parameters E,N,V... (the conserved mechanical parameters in the language of Ruppeiner) without invoking the thermodynamic limit. The topology is controlled by the curvature of S(E,N,V...). The most interesting region is the region of (wrong) positive maximum curvature, the region of phase-separation. This is demonstrated among others for the equilibrium of a typical non-extensive system, a self-gravitating and rotatin…
