The recently published PHENIX data of direct photons at low pt from Au+Au collisions at the BNL relativestic Heavy Ion Collider (RHIC) energy 200 GeV have attracted a lot of theoretic interest. Here I review our theoretical calculation which successfully reproduces the measured pt spectra of direct photons from Au+Au at different centralities over a wide pt range, in order to show a close relation between hadronic observables and those of direct photons.
We studied the effects of centrality fluctuation and deuteron formation on the cumulants ($C_n$) and correlation functions ($κ_n$) of protons up to sixth order in most central ($b<3$ fm) Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 3 GeV from a microscopic transport model (JAM). The results are presented as a function of rapidity acceptance within transverse momentum $0.4<p_{T}<2 $ GeV/$c$. We compared the results obtained by centrality bin width correction (CBWC) using charged reference particle multiplicity with CBWC done using impact parameter bins. It was found that at low energies the cen…
The production of light (anti)nuclei have been investigated using the dynamically constrained phase-space coalescence model based on the final-state hadrons generated by the PACIAE model in Cu+Cu collisions at $\sqrt{s_{\rm{NN}}}=200$GeV with $|η|<0.5$ and $0<p_T<8$GeV/c. The results show that there is a strong centrality dependence of yields of $\rm d$, $\rm\overline d$, $\rm ^3He$, $\rm^3\overline {He}$, $\rm ^4He$, and $\rm^4\overline {He}$, i.e., their yields decrease rapidly with the increase of centrality, and the greater the mass is, the greater the dependence shows; whereas their ratio…
Centrality, rapidity, and transverse-momentum dependence of gluon shadowing and antishadowing on $J/ψ$ production in $d$Au collisions at $\sqrt{s}$=200 GeV
Microscopic study of energy and centrality dependence of transverse collective flow in heavy-ion collisions
在两个微观输运模型中研究了能量从1 AGeV到160 AGeV的轻、重碰撞核系统中定向流和椭圆流的中心性依赖。在中快度范围内，无论碰撞离子的轰击能量和质量数如何，π指向流都具有负斜率。与此相反，定向流的核子消失，甚至发展中快度范围内的（半）周边碰撞在能量约11.6 A GeV和更高的逆流。流动消失的起源与核遮蔽有关。由于这种效应对于光系统来说更强，因此可以将其与夸克-胶子等离子体形成引起的类似现象区分开来。在后一种情况下，由于状态方程的软化，流的消失在重离子碰撞中应该最为明显。椭圆流的中心依赖性表明，随着入射能量的增加，<v_2（b）>分布中的最大值向非常外围的事件移动，与实验数据一致。这是热强子物质从重子到介子自由度转变的一个标志。
Elliptic flow ($v_2$) measurements of inclusive charged hadrons at mid-rapidity ($|η| <$ 1.0) in Au+Au collisions at $E_{lab} = 35\mathrm{~A~GeV}$ using the Parton Hadron String Dynamics (PHSD) model are presented as a function of centrality, transverse momentum ($p_\mathrm{T}$) and pseudo-rapidity ($η$). The $v_2$ results are obtained using the $η$-sub event plane method with respect to event plane angle ($ψ_{2}$) and participant plane angle ($ψ_{2}^{PP}$). $p_\mathrm{T}$-integrated charged hadron $v_2$ shows a strong centrality dependence in Au+Au collisions at $E_{lab} = 35\mathrm{~A~GeV}$.…
We take the experimental data for transverse momentum spectra of identified charged hadrons in different centrality classes for nucleus-nucleus (A+A) collisions at various Relativistic Heavy-Ion Collider (RHIC) energies measured by the STAR collaboration. We analyse these data in the framework of color string percolation model (CSPM) in order to extract various percolation parameters at different centralities at RHIC energies to study the effect of collision geometry and collision energy. We use these parameters to study the centrality dependent behaviour of initial temperature of the percolat…
Centrality, Rapidity and Transverse-Momentum Dependence of Cold Nuclear Matter Effects on J/Psi Production in d+Au, Cu+Cu and Au+Au Collisions at sqrt(s_NN)=200 GeV
We study the influence of the centrality definition and detector efficiency on the net-proton kurtosis for minimum bias Au+Au collisions at a beam energy of $\sqrt{s_{\mathrm{NN}}}= 7.7$ GeV by using the UrQMD model. We find that different ways of defining the centrality lead to different cumulant ratios. Moreover, we demonstrate that the kurtosis is suppressed for central collisions when a wider transverse momentum acceptance is used. Finally, the influence of a detector efficiency on the measured cumulant ratios is estimated.
Even-by-event hydrodynamical simulations for $\sqrt{s}_{NN}$=200 GeV Au+Au collisions and the correlation between flow coefficients and initial asymmetry measures
We analyzed the transverse momentum spectra of proton, deuteron and triton in Boron-Boron (B-B), Oxygen-Oxygen (O-O), and Calcium-Calcium (Ca-Ca) central collisions, as well as in several centrality bins in Gold-Gold (Au-Au) collisions at 39 GeV by using the blast wave model with Tsallis statistics. The bulk properties in terms of kinetic freeze-out temperature, transverse flow velocity and kinetic freeze-out volume are extracted from the model by the least square method. We observed that with increasing the rest mass of the particle, the kinetic freeze-out temperature becomes larger, while tr…
We evaluate centrality dependence of hyperon, $Λ, Ξ, Ω$ and $K$ meson yields from Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV using rate equation and compare with experimental observations. An increase in the yield per participating nucleon is observed with centrality. Higher rate of multistrange productions compared to single-strange are also observed in case of central collisions. Using rate equation or momentum integrated Boltzmann equation we discuss the yield microscopically which are then normalised with thermal pions to get the yield ratio,($H_s+\bar{H_s}$)/($π^++π^-$) at various centra…
Centrality and initial formation time dependence of the emission of thermal photons from fluctuating initial conditions at RHIC and LHC
对于RHIC的200 A GeV Au+Au碰撞和LHC的2.76 A TeV Pb+Pb碰撞，在$p_T >$ 1 GeV/ $c$范围内，理想流体动力学计算中的逐事件波动初始条件（IC）与平滑的初始状态平均分布相比，显著提高了热光子的产生。与平滑IC相比，波动IC中的“热点”或过密区域由于热辐射的强温度依赖性发射而产生更多的高$p_T$光子。这种增强预计将是更明显的外围碰撞，较低的光束能量，等离子体形成时间的较大值。适当归一化的热光子中心与周边产额之比（$R_{cp}^γ$）是研究初始条件下密度涨落及其大小的潜在探针。
