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Number-of-constituent-quark scaling of elliptic flow:a quantitative study

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Nuclear Science and Techniques 2022年第3期33卷 152-159页

作者： Meng Wang Jun-Qi Tao Hua Zheng Wen-Chao Zhang Li-Lin Zhu Aldo Bonasera School of Physics and Information Technology Shaanxi Normal UniversityXi’an 710119China Department of Physics Sichuan UniversityChengdu 610064China Cyclotron Institute Texas A&M UniversityCollege StationTX 77843USA Laboratori Nazionali del Sud INFNVia Santa Sofia6295123 CataniaItaly

The number-of-constituent-quark(NCQ)scaling behavior of the elliptic flow of identified particles produced in A+A collisions is studied quantitatively using an empirical function that fits the experimental v_(2) data available from the RHIC and *** most common approach for NCQ scaling involves(1)doing a scaling of the experimental v_(2) data of an identified particle with its NCQ,(2)doing the same to its transverse momentum or energy,then(3)combining all the scaled data and identifying the NCQ behavior by intuitively looking(since the measured experimental data are discrete).We define two variables(d_(1),d_(2))to describe NCQ scaling quantitatively and simultaneously,and identify the approximate region where the NCQ scaling *** approach could be applied to study NCQ or other scaling phenomena in future experiments.

关键词： Number-of-constituent-quark scaling Heavyion collisions elliptic flow

The Evolution of elliptic flow Under First Order Phase Transition

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Plasma Science and Technology 2012年第7期14卷 573-576页

作者：冯启春王清尚刘剑利任延宇张景波霍雷 Department of Physics Harbin Institute of Technology

elliptic flow for non-central Au＋Au collisions at √SNN=200 GeV is investigated with a 2＋1 dimensional hydrodynamic model. We analyze the softening effect by the velocity along the axis. The contribution of the elliptic flow from the QGP phase, mixed phase and hadron gas phase is studied. The relation between the sound horizon and evolution of the elliptic flow is discussed.

关键词： elliptic flow hydrodynamic model softening effect phase transition

Pion transverse-momentum spectrum, elliptic flow, and Hanbury-Brown-Twiss interferometry in a viscous granular source model

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Chinese Physics C 2017年第8期41卷 78-92页

作者： Jing Yang Wei-Ning Zhang Yan-Yu Ren School of Physics and Optoelectronic Technology Dalian University of Technology Dalian Liaoning 116024 China Department of Physics Harbin Institute of Technology Harbin Heilongjiang 150006 China

We examine the evolution of quark-gluon plasma（QGP） droplets with viscous hydrodynamics and analyze the pion transverse-momentum spectrum, elliptic flow, and Hanbury-Brown-Twiss（HBT） interferometry in a granular source model consisting of viscous QGP droplets. The shear viscosity of the QGP droplet speeds up and slows down the droplet evolution in the central and peripheral regions of the droplet, respectively. The effect of the bulk viscosity on the evolution is negligible. Although there are viscous effects on the droplet evolution, the pion momentum spectrum and elliptic flow change little for granular sources with and without viscosity. On the other hand,the influence of viscosity on HBT radius Rout is considerable. It makes Rout decrease in the granular source *** determine the model parameters of granular sources using the experimental data of pion transverse-momentum spectrum, elliptic flow, and HBT radii together, and investigate the effects of viscosity on the model parameters. The results indicate that the granular source model may reproduce the experimental data of pion transverse-momentum spectrum, elliptic flow, and HBT radii in heavy-ion collisions of Au-Au at√s（NN）=200 GeV and Pb-Pb at√s（NN） =2.76 Te V in different centrality intervals. The viscosity of the droplet leads to an increase in the initial droplet radius and a decrease of the source shell parameter in the granular source model.

关键词： high-energy heavy-ion collisions pion interferometry elliptic flow granular source viscous hydrodynamics

Nucleon effective mass splitting and density-dependent symmetry energy effects on elliptic flow in heavy ion collisions at Elab= 0.09 ~ 1.5 GeV/nucleon

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Chinese Physics C 2020年第7期44卷 103-110页

作者： Luyao Tong Pengcheng Li Fupeng Li Yongjia Wang Qingfeng Li Fanxin Liu Department of Physics Zhejiang University of TechnologyHangzhou 310023China School of Science Huzhou UniversityHuzhou 313000China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China Institute of Modem Physics Chinese Academy of SciencesLanzhou 730000China

By incorporating an iso spin-dependent form of the momentum-dependent potential in the ultra-relativistic quantum molecular dynamics(UrQMD)model,we systematically investigate effects of the neutron-proton effective mass splitting m*n-p=m*n-m*p/m and the density-dependent nuclear symmetry energy Esym(ρ)on the elliptic flow v2 in197Au+197 Au collisions at beam energies from 0.09 to 1.5 GeV/*** is found that at higher beam energies(≥0.25 GeV/nucleon)with the approximately 75 MeV difference in slopes of the two different Esym(ρ),and the variation of m*n-p ranging from-0.03 to 0.03 at saturation density with isospin asymmetryδ=(ρn-ρp)/ρ-0.2,the Esym(ρ)has a stronger influence on the difference in v2 between neutrons and protons,i.e.,v2n-v2p,than m*n-p ***,at lower beam energies(≤0.25 GeV/nucleon),v2n-v2p is sensitive to both the Esym(ρ)and the m****,the influence of m*n-p on v2n-v2p is more evident with the parameters of this study when using the soft,rather than stiff,symmetry energy.

关键词： nuclear symmetry energy heavy ion collision elliptic flow

Effects of mean-field and softening of equation of state on elliptic flow in Au+Au collisions at (~SNN)^(1/2)=5 GeV from the JAM model

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Chinese Physics C 2018年第2期42卷 112-118页

作者：陈佳敏罗晓峰刘峰奈良寧 Institute of Particle Physics and Key Laboratory of Quark&Lepton Physics (MOE) Central China Normal University Wuhan 430079 China Department of Physics and Astronomy University of California Los Angeles California 90095 USA Akita International University Yuwa Akita-city 010-1292 Japan Frankfurt Institute for Advanced Studies D-60438 Frankfurt am Main Germany

We perform a systematic study of elliptic flow（v2） in Au＋Au collisions at √^SNN = 5 GeV by using a microscopic transport model, JAM. The centrality, pseudorapidity, transverse momentum and beam energy dependence of v2 for charged as well as identified hadrons are studied. We investigate the effects of both the hadronic mean-field and the softening of equation of state（EoS） on elliptic flow. The softening of the EoS is realized by imposing attractive orbits in two body scattering, which can reduce the pressure of the system. We found that the softening of the EoS leads to the enhancement of v2, while the hadronic mean-field suppresses v2 relative to the cascade mode. It indicates that elliptic flow at high baryon density regions is highly sensitive to the EoS and the enhancement of v2 may probe the signature of a first-order phase transition in heavy-ion collisions at beam energies of a strong baryon stopping region.

关键词： heavy-ion collisions elliptic flow equation of state QCD phase transition

Energy dependence for directed and elliptic flow in intermediate-energy heavy ion collisions

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Chinese Physics C 2013年第1期37卷 62-65页

作者：颜廷志 School of Energy Resources and Power Engineering Northeast Dianli University

Differential and integrated directed flow and elliptic flow of light charged particles （z ≤ 2） are studied systematically for semi-central （b = 5 fm） 197Au＋197Au collisions at incident energies from 25 to 250 MeV/nucleon by the isospin-dependent quantum molecular dynamics model. The changes of directed and elliptic flow with incident energy reflect the dynamic competition between mean field and nucleon-nucleon collisions and also between collective rotation and expansion.

关键词： energy dependence directed flow elliptic flow

Eccentricity and elliptic flow at a fixed centrality in Au+Au collisions at (sNN)^(1/2)=200 GeV in an AMPT model

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Chinese Physics C 2013年第1期37卷 58-61页

作者：王美娟陈刚吴元芳 Physics Department China University of Geoscience Institute of Particle Physics Huazhong Normal University

In this paper, elliptic flow is studied at fixed centrality in Au＋Au collision at √sNN=200 GeV in the AMPT model. It is observed that with the participant increasing, elliptic flow has an increase or a decrease at different fixed impact parameter, but it does not have a trivial fluctuation. It is analyzed that the initial space anisotropy dominates the participant dependence of elliptic flow in near-central collisions（b=5 fm） and mid-central collisions（b=8 fm）, while the interaction between particles can mainly answer for the behavior of elliptic flow with participant in peripheral collisions （b=12 fm）. To distinguish the pure geometrical effect, elliptic flow scaled by initial eccentricity is studied. It is found that the ratio v2/ε increases with participant and reaches a saturation when the participant is large enough, indicating that the collision system may reach the local equilibrium.

关键词： elliptic flow initial eccentricity at a fixed centrality local equilibrium

Transverse radius dependence for transverse velocity and elliptic flow in intermediate energy HIC

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Chinese Physics C 2011年第5期35卷 459-462页

作者：颜廷志李杉 School of Energy Resources and Power Engineering Northeast Dianli University School of Science Northeast Dianli University

The mean transverse velocity and elliptic flow of light fragments （A≤2） as a function of transverse radius are studied for 25 MeV/nucleon 64Cu＋64Cu collisions with impact parameters 3–5 fm by the isospin- dependent quantum molecular dynamics model. By comparison between the in-plane and the out-of-plane transverse velocities, the elliptic flow dependence on the transverse radius can be understood qualitatively, and variation of the direction of the resultant force on the fragments can be investigated qualitatively.

关键词： mean transverse velocity elliptic flow intermediate energy HIC

Effects of elliptic flow and resonance decay process on the Kurtosis of net baryon distributions

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Chinese Physics C 2011年第5期35卷 467-470页

作者：肖凯周铀施梳苏吴科军刘峰 Institute of Particle Phyisics Huazhong Normal University (CCNU) Key Laboratory of Quark & Lepton Physics Huazhong Normal University (CCNU) Ministy of Education NIKHEF and Utrecht University

Kurtosis is regarded as a meaningful and promising observable in searching for the possible critical point predicted by QCD. In this paper, the effects of elliptic flow and resonance decay process on the Kurtosis have been studied with Monte Carlo event generators in Au ＋ Au collisions at sNN^（1/2） = 200 GeV. The results show that the Kurtosis is not sensitive to elliptic flow and resonance decay process.

关键词： the critical point the Kurtosis elliptic flow resonance decay process