We show that the event-by-event fluctuations of the transverse size of the initial source, which follow directly from the Glauber treatment of the earliest stage of relativistic heavy-ion collisions, cause, after hydrodynamic evolution, fluctuations of the transverse flow velocity at hadronic freeze-out. This in turn leads to event-by-event fluctuations of the average transverse momentum, p_T. Simulations with GLISSANDO for the Glauber phase, followed by a realistic hydrodynamic evolution and statistical hadronization carried out with THERMINATOR, lead to agreement with the RHIC data. In particular, the magnitude of the effect, its centrality dependence, and the weak dependence on the incident energy are properly reproduced. Our results show that bulk of the observed event-by-event p_T fluctuations may be explained by the fluctuations of the size of the initial source.
Thermal nature of charmonium transverse momentum spectra from Au-Au collisions at the highest energies available at the BNL Relativistic Heavy Ion Collider (RHIC)
Pseudorapidity profile of transverse momentum fluctuations in heavy ion collisions
本文研究了相对论重离子碰撞中粒子平均横向流的赝快度关联。本文采用3+1维粘性相对论流体动力学方法，在夸克Glauber Monte Carlo模型的初始条件下，研究了最近在$\sqrt{s_{NN}}=2760$ GeV下Pb+Pb碰撞中横向动量涨落的赝快度关联.我们发现模型预测和数据之间的良好协议。此外，我们还研究了另外两个观测量在不同快度仓中的平均横动量协方差。这些观测值在各种系统学下具有更好的稳定性，从而允许数据和模型之间的鲁棒性比较。横向流-横向流相关系数与不同拟速下的底层集体流相关系数直接相关。伪快度中的$p_T$分解破缺的3-bin测量给出了纵向平均横向流的可能去相关的估计。
The correlation between the harmonic flow and the transverse flow in relativistic heavy ion collisions is calculated in the hydrodynamic model. The partial correlation coefficient, corrected for fluctuations of multiplicity, is compared to experimental data. Estimators of the final transverse and harmonic flow are used to predict the value of the correlation coefficient from the moments of the initial distribution. A good description of the hydrodynamic simulation results is obtained if the estimator for the final transverse flow, besides the most important transverse size and entropy, include…
Transverse spherocity, an event shape observable, has a very unique capability to separate the events based on their geometrical shape, i.e. jetty and isotropic. In this work, we use transverse spherocity for the first time in heavy-ion collisions using A Multi-Phase Transport Model (AMPT). We obtain the transverse momentum spectra, integrated yield, mean transverse momentum and azimuthal anisotropy for identified particles in Xe-Xe collisions at $\sqrt{s_{\rm{NN}}} = 5.44$ TeV and Pb-Pb collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV. The indication of collectivity in heavy-ion collisions can b…
The charged-particle multiplicity distribution and the transverse-energy distribution measured in heavy-ion collisions at top RHIC and LHC energies are described using the two-component model approach based on a convolution of the Monte Carlo Glauber model with the Weibull model for particle production. The model successfully describes the multiplicity and transverse-energy distribution of minimum-bias collision data for a wide range of energies. The Weibull-Glauber model can be used to determine the centrality classes in heavy-ion collisions as an alternative to the conventional negative bino…
We show that an event-shape engineering based on the mean transverse momentum of charged hadrons, $[p_t]$, provides an optimal handle on the strength of the magnetic field created in central heavy-ion collisions at high energy. This is established through quantitative evaluations of the correlation existing between the event-by-event magnetic field produced by the spectator protons in 5.02 TeV Pb+Pb collisions and the event-by-event $[p_t]$ at a given collision centrality. We argue that the event selection based on $[p_t]$ provides a better handle on the magnetic field than the more traditiona…
Novel transverse-momentum technique is used to analyse charged-particle exclusive data for collective motion in the Ar+KCl reaction at 1.8 GeV/nucl. Previous analysis of this reaction, employing the standard sphericity tensor, revealed no significant effect. In the present analysis, collective effects are observed, and they are substantially stronger than in the Cugnon cascade model, but weaker than in the hydrodynamical model.
One of the event shape observables, the transverse spherocity ($S_0$), has been studied successfully in small collision systems such as proton-proton collisions at the LHC as a tool to separate jetty and isotropic events. It has a unique capability to distinguish events based on their geometrical shapes. In this work, we report the first implementation of transverse spherocity in heavy-ion collisions using a multi-phase transport model (AMPT). We have performed an extensive study of azimuthal anisotropy of charged particles produced in heavy-ion collisions as a function of transverse spherocit…
Chiral electric field in relativistic heavy-ion collisions at energies available at the BNL Relativistic Heavy Ion Collider and at the CERN Large Hadron Collider
The photon-photon interaction in ultra-relativistic heavy-ion collision is a source of the $(e^+,e^-)$ pairs. The photon-photon fusion leads the lepton creation in the broad configuration space around "collision" point. Those created close to heavy nuclei may undergo strong interaction with them. The impact parameter space distribution of electrons and positrons are calculated within the b-space EPA model of such collisions. The evolution due to the electromagnetic interaction of $(e^+,e^-)$ with nuclei is studied, and the distortion of rapidity and transverse momentum distributions are shown.…
Single Transverse-Spin Asymmetry in Large $P_T$ Open Charm Production at an Electron-Ion Collider
本文讨论了在半包容深度非弹性散射$e p^\uparrow \rightarrow e D X$中大横动量$D$介子产生中观察到的单横自旋不对称性。这种贡献体现为共线因子分解中的twist-3机制，它是由横极化核子内部的纯胶子关联，特别是三胶子关联效应引起的。用四个独立的胶子关联函数表示了首阶QCD中相应SSA的完整公式，并揭示了所产生的$D$ -介子的五种独立结构对方位角的依赖关系.本文给出了SSA公式在与未来电子离子对撞机相关的运动学上的数值计算。
Shannon information entropy provides an effective tool to study the evolution process in relativistic heavy-ion collisions. The time evolution process of thermodynamic entropy $S_{\rm thermal}$, multiple entropy $S_{\rm mul}$, and configuration entropy $S_{\rm conf}$ at RHIC is studied using the AMPT model to generate central Au-Au collisions. By superimposing the three kinds of information entropy, we can get a more complete information entropy of the system to describe the physical information of the relativistic heavy ion collision. The results show that the four stages of the time evolutio…
This article summarizes our present knowledge about nuclear matter at the highest energy densities and its formation in relativistic heavy ion collisions. We review what is known about the structure and properties of the quark-gluon plasma and survey the observables that are used to glean information about it from experimental data.
Re-Hardening of Hadron Transverse Mass Spectra in Relativistic Heavy-Ion Collisions
利用喷注实现的强子-弦级联模型，分析了相对论能量从2 A GeV到65+65 A GeV的重离子碰撞中质子和π介子的能谱.在这个能量范围内，强子横质谱首先表现出软化，直到SPS能量，和再硬化可能出现在RHIC能量。由于强子物质在较高的能量密度下只表现出软化，这种光谱的再硬化可以被解释为夸克-胶子等离子体形成的一个很好的标志。
Mapping the transverse spin sum rule in position space
CPHT, CNRS, École polytechnique, Institut Polytechnique de Paris（法国国家科学研究中心、巴黎综合理工学院、巴黎理工学院）；Department of Physics, Indian Institute of Technology Bombay（印度孟买理工学院物理系）
