Hydrodynamic fluctuations have been studied in a wide variety of physical, chemical, and biological phenomena in the past decade. In high energy heavy ion collisions, there will be intrinsic fluctuations even if the initial conditions are fixed. Fluctuations will be greatly enhanced if the trajectory in the plane of temperature versus chemical potential passes near a critical point. We construct a model for the thermal conductivity which diverges at the critical point with the correct critical exponents, and use it in a simple illustrative model of a heavy ion collision. The proton correlation function is sensitive to the presence of the critical point.
Recent theoretical developments of relativistic hydrodynamics applied to ultrarelativistic heavy-ion collisions are briefly reviewed. In particular, the concept of a formal gradient expansion is discussed, which is a tool to compare different hydrodynamic models with underlying microscopic theories.
Due to large pressure gradients at early times, standard hydrodynamic model simulations of relativistic heavy-ion collisions do not become reliable until $O(1)$\,fm/$c$ after the collision. To address this one often introduces a pre-hydrodynamic stage that models the early evolution microscopically, typically as a conformal, weakly interacting gas. In such an approach the transition from the pre-hydrodynamic to the hydrodynamic stage is discontinuous, introducing considerable theoretical model ambiguity. Alternatively, fluids with large anisotropic pressure gradients can be handled macroscopic…
We investigate hadronic particle spectra and flow characteristics of heavy-ion reactions in the FAIR/NICA energy range of $1\ A{\rm GeV} \le E_{\rm lab} \le 10\ A{\rm GeV}$ within a relativistic ideal hydrodynamic one-fluid approach. The particlization is realized by sampling the Cooper-Frye distribution for a grand canonical hadron gas on a hypersurface of constant energy density. Results of the hydrodynamic calculations for different underlying equations of state are presented and compared with experimental data and microscopic transport simulations. The sensitivity of the approach to physic…
We calculate the squeezed back-to-back correlation (BBC) functions of $ϕϕ$ and $K^+K^-$ for heavy-ion collisions at RHIC and LHC energies, using ($2+1$)-dimensional hydrodynamics with fluctuating initial conditions. The BBC functions averaged over event-by-event calculations for many events for the hydrodynamic sources are smoothed as a function of the particle momentum. For heavy-ion collisions of Au+Au at $\sqrt{s_{NN}}=200$ GeV, the BBC functions are larger than those for collisions of Pb+Pb at $\sqrt{s_{NN}}=2.76$ TeV. The BBC of $ϕϕ$ may possibly be observed in peripheral collisions at th…
Numerical Analyses of CERN 200GeV/A Heavy-Ion Collisions Based on a Hydrodynamical Model with Phase Transition
基于一个考虑相变的流体动力学模型，对近年来的高能重离子碰撞实验进行了数值分析，讨论了QGP流体初始状态随碰撞核质量的系统变化.在前一篇文章中，我们建立了一个具有相变的夸克-胶子等离子体的（3+1）维流体动力学模型，并对时空演化进行了详细的数值讨论。本文将数值解与CERN WA 80和NA 35给出的强子分布进行了比较。通过对各种碰撞核实验的系统分析，讨论了流体动力学模型的初始参数对碰撞核质量的依赖关系。此外，我们还外推了150 GeV/A铅-铅碰撞的强子分布。
Relativistic Heavy Ion Collisions: Viscous Hydrodynamic Simulations and Final State Interactions
在这篇论文中，我介绍了相对论性重离子碰撞，并描述了理解它们的理论方法--特别是粘性流体动力学模拟和末态相互作用的研究。对相对论重离子对撞机（RHIC）上成功的理想流体动力学模型进行了推广，并进行了粘性流体动力学模拟。这是通过利用最近导出的完全共形不变的二阶相对论粘性流体动力学方程。给出了sqrt{sNN}=200 GeV Au+Au RHIC碰撞中多重数、径向流和椭圆流的计算结果，并给出了我们的流体动力学模型与实验数据相一致的剪切粘滞率与熵密度之比η/s的范围。此外，在大型强子对撞机（LHC）计划的sqrt{s_NN}=5.5 TeV Pb+Pb和sqrt{s}=14 TeV p+p碰撞进行了模拟。与顶能RHIC碰撞相比，Pb+Pb碰撞的椭圆流系数v_2预计要大10%，而质子碰撞的椭圆流系数v_2预计为零，除非eta/s < 0.08。最后，在扭曲波发射函数（DWEF）模型中研究了末态相互作用。本文对DWEF模型作了进一步的研究，并计算了π光学势形式的末态相互作用对椭圆流系数v_2的影响在~20%水平。
The (viscous) anisotropic hydrodynamic approach, especially after perturbative inclusion of all residual viscous terms, has been shown to dramatically outperform viscous hydrodynamics in several simplified situations for which exact solutions exist but which share with realistic expansion scenarios the problem of large dissipative currents. We will report on the present status of applying viscous anisotropic hydrodynamics in a highly efficient simulation of the full three-dimensional quark-gluon plasma. Results from accelerated $3{+}1$-dimensional viscous hydrodynamic simulations using graphic…
Multiplicity fluctuations are one of the most crucial observables in the Beam Energy Scan program of the Relativistic Heavy Ion Collider. It is understood that they can be utilized to probe the whereabouts of the critical point on the phase diagram of the QCD matter. However, a significant portion of these fluctuations is, apart from that related to the QCD phase transition, attributed to the other origins, which we refer to as "noncritical" ones. The present study is dedicated to the noncritical aspects of the multiplicity fluctuations in heavy-ion collisions. In particular, we focus on those…
Charge fluctuations for a baryon-neutral quark-gluon plasma have been calculated in lattice gauge theory. These fluctuations provide a well-posed rigorous representation of the quark chemistry of the vacuum for temperatures above T_c >~ 155 MeV. Due to the finite lifetime and spatial extent of the fireball created in relativistic heavy ion collisions, charge-charge correlations can only equilibrate for small volumes due to the finite time required to transport charge. This constraint leads to charge correlations at finite relative position that evolve with time. The source and evolution of suc…
This contribution presents a theoretical overview of hydrodynamic modelling of heavy-ion collisions, with highlights on some recent developments. In particular, the formulation of anisotropic hydrodynamics, the role of hydrodynamic fluctuations, and the non-linear coupling of flow coefficients will be discussed.
An introductory overview of electromagnetic probes in ultra-relativistic heavy-ion collisions is provided. Experimental evidence supporting the production of thermal photons and dileptons in heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) are reviewed. Thermal electromagnetic emission evaluated from hydrodynamical models of collisions is discussed.
In this talk we will discuss the recent advances in describing heavy-quark dynamics in the quark-gluon plasma (QGP), which evolves hydrodynamically. Special emphasis is put on the collective flow of the heavy-quarks with the medium constituents, for which we present our latest results obtained within the MC@sHQ+EPOS2 model at $\sqrt{s}=5$~TeV.
