The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Y. G. - One of the best experts on this subject based on the ideXlab platform.
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extracting jet Transport parameter hat q from a Multiphase Transport model
European Physical Journal A, 2020Co-Authors: Fengchu Zhou, Y. G.Abstract:Within a Multiphase Transport model with a string-melting scenario, the jet Transport parameter $$\hat{q}$$ is extracted in Au+Au collisions at $$\sqrt{s_{NN} } $$= 200 GeV and Pb+Pb collisions at $$\sqrt{s_{NN} } $$= 2.76 TeV. The jet Transport parameter $$\hat{q}$$ is a key parameter in jet-quenching phenomena, which depends not only on the temperature of the QCD medium but also on jet energy. We observe that $$\hat{q}$$ increases with increasing of the jet energy for both the partonic phase and the hadronic phase. The energy and path length dependences of $$\hat{q}$$ in full heavy-ion evolution are consistent with the expectations of jet quenching. The correlation between jet Transport parameter $$\hat{q}$$ and dijet transverse momentum asymmetry $$A_J$$ is investigated. It is interesting to find that dijets with larger $$A_J$$ have larger length-averaged $$\hat{q}$$ values. Our study suggests that dijets with different $$A_J$$ values can provide versatile tools for studying jet quenching and extracting jet Transport parameters.
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Collision system size scan of collective flows in relativistic heavy-ion collisions
Physics Letters B, 2020Co-Authors: Shenghui Zhang, Y. G., Jinhui Chen, Qi-ye Shou, Chen ZhongAbstract:Abstract Initial geometrical distribution and fluctuation can affect the collective expansion in relativistic heavy-ion collisions. This effect may be more evident in small system (such as B + B) than in large one (Pb + Pb). This work presents the collision system dependence of collective flows and discusses about effects on collective flows from initial fluctuations in a framework of a Multiphase Transport model. The results shed light on system scan on experimental efforts to small system physics.
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charge asymmetry dependence of flow and a novel correlator to detect the chiral magnetic wave in a Multiphase Transport model
Physical Review C, 2019Co-Authors: Diyu Shen, Y. G., G. L., S. Zhang, Jing Chen, Q Y Shou, C. ZhongAbstract:In a Multiphase Transport model with the initial electric quadrupole moment, we studied and discussed the charge asymmetry (${A}_{\mathrm{ch}}$) dependence of flow at varied kinematic windows in semicentral $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}$ = 200 GeV. We then proposed a novel correlator $W$ which specifically focuses on the difference of elliptic flow between positively and negatively charged hadrons induced by the chiral magnetic wave and, more importantly, is irrelevant to the ambiguous ${A}_{\mathrm{ch}}$. We found that the distribution of the second-order correlator ${W}_{2}$ displays a convex structure in the absence of the quadrupole and a concave shape in the presence of the quadrupole. We then studied the response of ${W}_{n}$ for both signal and resonance background in a toy model and in analytical calculation. Such a method provides a new way to detect the chiral magnetic wave.
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electromagnetic fields in small systems from a Multiphase Transport model
Physical Review C, 2018Co-Authors: Xinli Zhao, Y. G.Abstract:We calculate the electromagnetic fields generated in small systems by using a Multiphase Transport (AMPT) model. Compared to $A+A$ collisions, we find that the absolute electric and magnetic fields are not small in $p$+Au and $d$+Au collisions at energies available at the BNL Relativistic Heavy Ion Collider and in $p$+Pb collisions at energies available at the CERN Large Hadron Collider. We study the centrality dependencies and the spatial distributions of electromagnetic fields. We further investigate the azimuthal fluctuations of the magnetic field and its correlation with the fluctuating geometry using event-by-event simulations. We find that the azimuthal correlation $\left\langle \cos2(\Psi_B - \Psi_{2}) \right\rangle$ between the magnetic field direction and the second harmonic participant plane is almost zero in small systems with high multiplicities, but not in those with low multiplicities. This indicates that the charge azimuthal correlation, $\left\langle \cos(\phi_{\alpha}+\phi_{\beta} - 2\Psi_{RP}) \right\rangle$, is not a valid probe to study the chiral magnetic effect (CME) in small systems with high multiplicities. However, we suggest searching for possible CME effects in small systems with low multiplicities.
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a study on k 892 0 and ϕ 1020 production in p pb and pb pb collisions at the lhc from a Multiphase Transport model
Journal of Physics G, 2018Co-Authors: Xueying Liu, Y. G., Jing ChenAbstract:Using a Multiphase Transport model (AMPT) that includes both initial partonic and final hadronic interactions, we study the $K^{*}(892)^0$ and $\phi(1020)$ production at the Large Hadron Collider. It is found that a hadronic cascade time of t$\geq$10 fm/c describes the strong suppression of $K^{*0}/K^-$ ratio in central Pb-Pb collision at~\srt = 2.76 TeV, while for the p-Pb collisions at~\srt = 5.02 TeV, a lower limit of hadronic interaction t$\geq$4 fm/c is derived by comparison with the collision system dependence of $K^{*0}/K^{-}$ and $\phi/K^{-}$ ratios. Detail studies on transverse momentum dependence of $K^{*0}/K^-$, $\phi/K^{-}$ and $K^{*0}/\pi$, $\phi/\pi$ ratios, the elliptic flow ($v_2$) of $K^{*0}$ and $\phi$ shows clear evidence on the dominance of rescattering over regeneration of $K^{*0}$ in heavy-ion collisions at LHC energy. Our calculation describes the flat $p/\phi$ ratio well in central Pb-Pb collisions at $0lp_Tl5$ GeV/c, indicating fluid like dynamics in the AMPT model.
C. Zhong - One of the best experts on this subject based on the ideXlab platform.
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Charge asymmetry dependence of flow and a novel correlator to detect the chiral magnetic wave in a Multiphase Transport model
Physical Review C, 2019Co-Authors: Diyu Shen, Jinhui Chen, Song Zhang, Qi-ye Shou, C. ZhongAbstract:In a Multiphase Transport model with the initial electric quadrupole moment, we studied and discussed the charge asymmetry ($A_{\rm ch}$) dependence of flow at varied kinematic windows in semi-central Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV. We then proposed a novel correlator $W$ which specially focuses on the difference of elliptic flow between positively and negatively charged hadrons induced by the chiral magnetic wave and, more importantly, is irrelevant to the ambiguous $A_{\rm ch}$. We found that the distribution of the second order correlator $W_2$ displays a convex structure in the absence of the quadrupole and a concave shape in the presence of the quadrupole. We also studied the response of $W_n$ for both signal and resonance background in a toy model and in analytical calculation. Such a method provides a new way to detect the chiral magnetic wave.
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charge asymmetry dependence of flow and a novel correlator to detect the chiral magnetic wave in a Multiphase Transport model
Physical Review C, 2019Co-Authors: Diyu Shen, Y. G., G. L., S. Zhang, Jing Chen, Q Y Shou, C. ZhongAbstract:In a Multiphase Transport model with the initial electric quadrupole moment, we studied and discussed the charge asymmetry (${A}_{\mathrm{ch}}$) dependence of flow at varied kinematic windows in semicentral $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}$ = 200 GeV. We then proposed a novel correlator $W$ which specifically focuses on the difference of elliptic flow between positively and negatively charged hadrons induced by the chiral magnetic wave and, more importantly, is irrelevant to the ambiguous ${A}_{\mathrm{ch}}$. We found that the distribution of the second-order correlator ${W}_{2}$ displays a convex structure in the absence of the quadrupole and a concave shape in the presence of the quadrupole. We then studied the response of ${W}_{n}$ for both signal and resonance background in a toy model and in analytical calculation. Such a method provides a new way to detect the chiral magnetic wave.
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ω and ϕ in au au collisions at and 11 5 gev from a Multiphase Transport model
Chinese Physics C, 2017Co-Authors: J. H. Chen, Y. G., S. Zhang, C. ZhongAbstract:Within the framework of a Multiphase Transport model, we study the production and properties of Omega and phi in Au + Au collisions with a new set of parameters for root(NN)-N-S = 200 GeV and with the original set of parameters for root(NN)-N-S = 11.5 GeV. The AMPT model with string melting provides a reasonable description at root(NN)-N-S = 200 GeV, while the default AMPT model describes the data well at root(NN)-N-S = 11.5 GeV. This indicates that the system created at top RHIC energy is dominated by partonic interactions, while hadronic interactions become important at lower beam energy, such as root(NN)-N-S = 11.5 GeV. The comparison of N (Omega(+)Omega(-))/[2N(phi)] ratio between data and calculations further supports the argument. Our calculations can generally describe the data of nuclear modification factor as well as elliptic flow.
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Low-mass vector meson production at forward rapidity in p+p and d+Au collisions at \srt = 200 GeV from a Multiphase Transport model
Nuclear Science and Techniques, 2016Co-Authors: Jinhui Chen, Song Zhang, C. ZhongAbstract:Low-mass vector meson (\(\rho , \omega \), and \(\phi \)) production at forward rapidity in p+p and d+Au collisions at \(\sqrt{s_{{\rm NN}}}\) = 200 GeV is studied within the framework of a Multiphase Transport model (AMPT). Detailed investigations, including the transverse momentum and the rapidity dependence of low-mass vector meson production in the AMPT model, show that the hadron interaction process is important for a quantitative description of the \(\rho \) and \(\omega \) data. But for the \(\phi \) meson, the strange quark production in the AMPT model with the string melting scenario describes the data reasonably well, while the default AMPT model under-predicts the data. The \({\rm N}(\phi )/{\rm N} (\rho + \omega )\) ratio from the AMPT model with the string melting scenario perfectly describes the data in p+p collisions. For the d+Au collisions, an increased trend of this ratio vs. transverse momentum and the number of participants are observed from the AMPT model. Our results indicate that a precise measurement of the \({\rm N}(\phi )/ {\rm N} (\rho + \omega )\) ratio in d+Au and Au+Au collisions will shed more light on the strangeness production and its dynamics in quark–gluon plasma.
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low mass vector meson production at forward rapidity in p p and d au collisions at srt 200 gev from a Multiphase Transport model
Nuclear Science and Techniques, 2016Co-Authors: Jing Chen, Y. G., Song Zhang, C. ZhongAbstract:Low-mass vector meson (\(\rho , \omega \), and \(\phi \)) production at forward rapidity in p+p and d+Au collisions at \(\sqrt{s_{{\rm NN}}}\) = 200 GeV is studied within the framework of a Multiphase Transport model (AMPT). Detailed investigations, including the transverse momentum and the rapidity dependence of low-mass vector meson production in the AMPT model, show that the hadron interaction process is important for a quantitative description of the \(\rho \) and \(\omega \) data. But for the \(\phi \) meson, the strange quark production in the AMPT model with the string melting scenario describes the data reasonably well, while the default AMPT model under-predicts the data. The \({\rm N}(\phi )/{\rm N} (\rho + \omega )\) ratio from the AMPT model with the string melting scenario perfectly describes the data in p+p collisions. For the d+Au collisions, an increased trend of this ratio vs. transverse momentum and the number of participants are observed from the AMPT model. Our results indicate that a precise measurement of the \({\rm N}(\phi )/ {\rm N} (\rho + \omega )\) ratio in d+Au and Au+Au collisions will shed more light on the strangeness production and its dynamics in quark–gluon plasma.
Ziwei Lin - One of the best experts on this subject based on the ideXlab platform.
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enhanced production of strange baryons in high energy nuclear collisions from a Multiphase Transport model
Physical Review C, 2020Co-Authors: Jing Chen, Tianhao Shao, Ziwei LinAbstract:We introduce additional coalescence factors for the production of strange baryons in a Multiphase Transport (AMPT) model in order to describe the enhanced production of multistrange hadrons observed in $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{{s}_{NN}}=2.76\phantom{\rule{0.28em}{0ex}}\mathrm{TeV}$ at the Large Hadron Collider (LHC) and $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}=200\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}$ at Relativistic Heavy-Ion Collider (RHIC). This extended AMPT model is found to also give a reasonable description of the multiplicity dependence of the strangeness enhancement observed in high multiplicity events in $pp$ collisions at $\sqrt{s}=7\phantom{\rule{0.28em}{0ex}}\mathrm{TeV}$ and $p$-Pb collisions at $\sqrt{{s}_{NN}}=5.02\phantom{\rule{0.28em}{0ex}}\mathrm{TeV}$. We find that the coalescence factors depend on the system size but not much on whether the system is produced from $\mathrm{A}+\mathrm{A}$ or $p+\mathrm{A}$ collisions. The extended AMPT model thus provides a convenient way to model the mechanism underlying the observed strangeness enhancement in collisions of both small and large systems at RHIC and LHC energies.
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energy dependence study of directed flow in au au collisions using an improved coalescence in a Multiphase Transport model
Physical Review C, 2019Co-Authors: K Nayak, Ziwei Lin, S S ShiAbstract:The rapidity-odd component of directed flow (${v}_{1}$) of identified hadrons (${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$, ${K}^{\ifmmode\pm\else\textpm\fi{}}$, ${K}_{S}^{0}$, $p$, $\overline{p}$, $\ensuremath{\phi}$, $\mathrm{\ensuremath{\Xi}}$, $\overline{\mathrm{\ensuremath{\Xi}}}$, $\mathrm{\ensuremath{\Lambda}}$, $\overline{\mathrm{\ensuremath{\Lambda}}}$) and partons ($u$, $\overline{u}$, $d$, $\overline{d}$, $s$, $\overline{s}$) in $\mathrm{Au}+\mathrm{Au}$ collisions at various beam energies ($\sqrt{{s}_{NN}}=7.7$, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4, 200 GeV) is analyzed using a Multiphase Transport model. A data driven approach (inspired from the experimental analysis) is performed here to distinguish the Transported and produced quarks which are found to have different directed flow values at various collision beam energies. The coalescence sum rule (number of constituent quark scaling) violation is observed at lower energies where hadronic matters dominate. The strange quark ($s$) and $\ensuremath{\phi}$ meson slope ($d{v}_{1}/dy$) show a double sign change around 14.5 GeV unlike other partons and hadrons. It suggests that the strange quark is more sensitive to the softening of the equation of state.
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Update of a Multiphase Transport model with modern parton distribution functions and nuclear shadowing
Physical Review C, 2019Co-Authors: Chao Zhang, Shusu Shi, Liang Zheng, Feng Liu, Ziwei LinAbstract:A Multiphase Transport (AMPT) model has been successful in explaining a wide range of observables in relativistic heavy ion collisions. In this work, we implement a newer set of free proton parton distribution functions and an impact parameter-dependent nuclear shadowing in the AMPT model. After refitting the parameters of the two-component initial condition model to the experimental data on $pp$ and $p\overline{p}$ total and inelastic cross sections from $\sqrt{s}\ensuremath{\sim}$ 4 GeV to 13 TeV, we study particle productions in $pp$ and $AA$ collisions. We show that the updated AMPT model with string melting can reasonably describe the overall particle yields and transverse momentum spectra for both $pp$ and $AA$ collisions at RHIC and LHC energies after we introduce a nuclear scaling of the minijet transverse momentum cutoff for $AA$ collisions at LHC energies that is motivated by the color glass condensate. Since heavy flavor and $\mathrm{high}\ensuremath{-}{p}_{\mathrm{T}}$ particles are produced by perturbative-QCD processes and thus directly depend on parton distribution functions of nuclei, the updated AMPT model is expected to provide a more reliable description of these observables.
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Two-particle angular correlations in heavy ion collisions from a Multiphase Transport model
Physical Review C, 2019Co-Authors: L. Y. Zhang, Ziwei Lin, Jinhui Chen, Song ZhangAbstract:We extend our earlier study on two-particle angular correlations in $pp$ collisions at low transverse momentum (${p}_{T}$) to $p$-Pb, Pb-Pb, and Au-Au collisions at BNL Relativistic Heavy Ion Collider and CERN Large Hadron Collider energies. We mainly use the string melting version of a Multiphase Transport model with improved quark coalescence for this study. We start from the analysis of ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}},\phantom{\rule{0.16em}{0ex}}{K}^{\ifmmode\pm\else\textpm\fi{}}$, and $p$($\overline{p}$) ${p}_{T}$ and rapidity distributions at different centralities. We then focus on two-particle angular correlations in $p$-Pb collisions at $\sqrt{{s}_{NN}}=5.02$ TeV and Pb-Pb collisions at $\sqrt{{s}_{NN}}=2.76$ TeV. For $p$-Pb collisions, a near side depression in the angular correlation is observed for low ${p}_{T}$ proton pairs and $\mathrm{\ensuremath{\Lambda}}$ pairs but not for pion pairs or kaon pairs, similar to our earlier finding for $pp$ collisions at $\sqrt{s}=7$ TeV. This is also the case for very low multiplicity Pb-Pb and Au-Au collisions. We also find that parton interactions and the improved quark coalescence are mainly responsible for the depression feature in baryon pair angular correlations. However, no such baryon-baryon anticorrelations are observed in Pb-Pb and Au-Au collisions at higher multiplicities. Therefore our results suggest that low ${p}_{T}$ baryon-baryon angular anticorrelations have a strong multiplicity dependence.
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Multiphase Transport model predictions of isobaric collisions with nuclear structure from density functional theory
Physical Review C, 2018Co-Authors: Jie Zhao, Ziwei Lin, Hanzhong Zhang, Xiaobao Wang, Caiwan Shen, Fuqiang WangAbstract:Isobaric $_{44}^{96}\mathrm{Ru}\phantom{\rule{0.16em}{0ex}}+\phantom{\rule{0.16em}{0ex}}_{44}^{96}\mathrm{Ru}$ and $_{40}^{96}\mathrm{Zr}\phantom{\rule{0.16em}{0ex}}+\phantom{\rule{0.16em}{0ex}}_{40}^{96}\mathrm{Zr}$ collisions were performed at the Relativistic Heavy Ion Collider in 2018. Using the ``a Multiphase Transport'' model with nuclear structures calculated by the density functional theory (DFT), we make predictions for the charged hadron multiplicity distributions and elliptic azimuthal anisotropies in these collisions. Emphases are put on the relative differences between the two collision systems that can decisively discriminate DFT nuclear distributions from the commonly used Woods-Saxon densities.
Jinhui Chen - One of the best experts on this subject based on the ideXlab platform.
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Collision system size scan of collective flows in relativistic heavy-ion collisions
Physics Letters B, 2020Co-Authors: Shenghui Zhang, Y. G., Jinhui Chen, Qi-ye Shou, Chen ZhongAbstract:Abstract Initial geometrical distribution and fluctuation can affect the collective expansion in relativistic heavy-ion collisions. This effect may be more evident in small system (such as B + B) than in large one (Pb + Pb). This work presents the collision system dependence of collective flows and discusses about effects on collective flows from initial fluctuations in a framework of a Multiphase Transport model. The results shed light on system scan on experimental efforts to small system physics.
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Charge asymmetry dependence of flow and a novel correlator to detect the chiral magnetic wave in a Multiphase Transport model
Physical Review C, 2019Co-Authors: Diyu Shen, Jinhui Chen, Song Zhang, Qi-ye Shou, C. ZhongAbstract:In a Multiphase Transport model with the initial electric quadrupole moment, we studied and discussed the charge asymmetry ($A_{\rm ch}$) dependence of flow at varied kinematic windows in semi-central Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV. We then proposed a novel correlator $W$ which specially focuses on the difference of elliptic flow between positively and negatively charged hadrons induced by the chiral magnetic wave and, more importantly, is irrelevant to the ambiguous $A_{\rm ch}$. We found that the distribution of the second order correlator $W_2$ displays a convex structure in the absence of the quadrupole and a concave shape in the presence of the quadrupole. We also studied the response of $W_n$ for both signal and resonance background in a toy model and in analytical calculation. Such a method provides a new way to detect the chiral magnetic wave.
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Two-particle angular correlations in heavy ion collisions from a Multiphase Transport model
Physical Review C, 2019Co-Authors: L. Y. Zhang, Ziwei Lin, Jinhui Chen, Song ZhangAbstract:We extend our earlier study on two-particle angular correlations in $pp$ collisions at low transverse momentum (${p}_{T}$) to $p$-Pb, Pb-Pb, and Au-Au collisions at BNL Relativistic Heavy Ion Collider and CERN Large Hadron Collider energies. We mainly use the string melting version of a Multiphase Transport model with improved quark coalescence for this study. We start from the analysis of ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}},\phantom{\rule{0.16em}{0ex}}{K}^{\ifmmode\pm\else\textpm\fi{}}$, and $p$($\overline{p}$) ${p}_{T}$ and rapidity distributions at different centralities. We then focus on two-particle angular correlations in $p$-Pb collisions at $\sqrt{{s}_{NN}}=5.02$ TeV and Pb-Pb collisions at $\sqrt{{s}_{NN}}=2.76$ TeV. For $p$-Pb collisions, a near side depression in the angular correlation is observed for low ${p}_{T}$ proton pairs and $\mathrm{\ensuremath{\Lambda}}$ pairs but not for pion pairs or kaon pairs, similar to our earlier finding for $pp$ collisions at $\sqrt{s}=7$ TeV. This is also the case for very low multiplicity Pb-Pb and Au-Au collisions. We also find that parton interactions and the improved quark coalescence are mainly responsible for the depression feature in baryon pair angular correlations. However, no such baryon-baryon anticorrelations are observed in Pb-Pb and Au-Au collisions at higher multiplicities. Therefore our results suggest that low ${p}_{T}$ baryon-baryon angular anticorrelations have a strong multiplicity dependence.
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Two-particle angular correlations in p p and p -Pb collisions at energies available at the CERN Large Hadron Collider from a Multiphase Transport model
Physical Review C, 2018Co-Authors: L. Y. Zhang, Ziwei Lin, Jinhui Chen, Song ZhangAbstract:We apply a Multiphase Transport (AMPT) model to study two-particle angular correlations in $pp$ collisions at $\sqrt{s}=7\phantom{\rule{0.16em}{0ex}}\mathrm{TeV}$. In addition to being able to describe the angular correlation functions of meson-meson pairs, a large improvement for the angular correlations of baryon-baryon and antibaryon-antibaryon is achieved. We further find that the AMPT model with new quark coalescence provides an even better description on the anticorrelation feature of baryon-baryon correlations observed in the experiments. We also extend the study to $p$-Pb collisions at $\sqrt{s}=5.02\phantom{\rule{0.16em}{0ex}}\mathrm{TeV}$ and obtained similar results. These results help us better understand the particle production mechanism in $pp$ and $p$-Pb collisions at Large Hadron Collider energies.
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Explore the QCD phase transition phenomena from a Multiphase Transport model
Science China Physics Mechanics & Astronomy, 2018Co-Authors: Xiao-hai Jin, Ziwei Lin, Jinhui Chen, G. L., Song ZhangAbstract:We study the phase structure of QCD matter in the framework of a Multiphase Transport model by implementing a strong local parton density fluctuation scenario. Our calculations on the beam energy dependence of net-proton high moment show that local parton density fluctuation only has a small effect. But it becomes important when all baryons are included. We then study the effect on elliptic flow and find that an enhanced local parton density fluctuation leads to a significant effect on protons but a small effect on pions. Our study provides a reference of Transport dynamics on QCD phase transition phenomena and will be relevant for the upcoming phase II of the beam energy scan program at RHIC.
Song Zhang - One of the best experts on this subject based on the ideXlab platform.
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Nuclear system size scan for freeze-out properties in relativistic heavy-ion collisions by using a Multiphase Transport model
Physical Review C, 2020Co-Authors: Dong-fang Wang, Song ZhangAbstract:A system size scan program was recently proposed for the STAR experiments at the Relativistic Heavy Ion Collider (RHIC). In this study, we employ a Multiphase Transport (ampt) model for considering the bulk properties at the freeze-out stage for B10+B10, C12+C12, O16+O16, Ne20+Ne20, Ca40+Ca40, Zr96+Zr96, and Au197+Au197 collisions at RHIC energies sNN of 200, 20, and 7.7 GeV. The results for Au197+Au197 collisions are comparable with those of previous experimental STAR data. The transverse momentum pT spectra of charged particles (π±, K±, p, and p¯) at the kinetic freeze-out stage, based on a blast-wave model, are also discussed. In addition, we use a statistical thermal model to extract the parameters at the chemical freeze-out stage, which agree with those from other thermal model calculations. It was found that there is a competitive relationship between the kinetic freeze-out parameter Tkin and the radial expansion velocity βT, which also agrees with the STAR or ALICE results. We found that the chemical freeze-out strangeness potential μs remains constant in all collision systems and that the fireball radius R is dominated by NPart, which can be well fitted by a function of aNPartb with b≈1/3. In addition, we calculated the nuclear modification factors for different collision systems with respect to the B10+B10 system, and found that they present a gradual suppression within a higher pT range from small to large systems.
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Charge asymmetry dependence of flow and a novel correlator to detect the chiral magnetic wave in a Multiphase Transport model
Physical Review C, 2019Co-Authors: Diyu Shen, Jinhui Chen, Song Zhang, Qi-ye Shou, C. ZhongAbstract:In a Multiphase Transport model with the initial electric quadrupole moment, we studied and discussed the charge asymmetry ($A_{\rm ch}$) dependence of flow at varied kinematic windows in semi-central Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV. We then proposed a novel correlator $W$ which specially focuses on the difference of elliptic flow between positively and negatively charged hadrons induced by the chiral magnetic wave and, more importantly, is irrelevant to the ambiguous $A_{\rm ch}$. We found that the distribution of the second order correlator $W_2$ displays a convex structure in the absence of the quadrupole and a concave shape in the presence of the quadrupole. We also studied the response of $W_n$ for both signal and resonance background in a toy model and in analytical calculation. Such a method provides a new way to detect the chiral magnetic wave.
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Two-particle angular correlations in heavy ion collisions from a Multiphase Transport model
Physical Review C, 2019Co-Authors: L. Y. Zhang, Ziwei Lin, Jinhui Chen, Song ZhangAbstract:We extend our earlier study on two-particle angular correlations in $pp$ collisions at low transverse momentum (${p}_{T}$) to $p$-Pb, Pb-Pb, and Au-Au collisions at BNL Relativistic Heavy Ion Collider and CERN Large Hadron Collider energies. We mainly use the string melting version of a Multiphase Transport model with improved quark coalescence for this study. We start from the analysis of ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}},\phantom{\rule{0.16em}{0ex}}{K}^{\ifmmode\pm\else\textpm\fi{}}$, and $p$($\overline{p}$) ${p}_{T}$ and rapidity distributions at different centralities. We then focus on two-particle angular correlations in $p$-Pb collisions at $\sqrt{{s}_{NN}}=5.02$ TeV and Pb-Pb collisions at $\sqrt{{s}_{NN}}=2.76$ TeV. For $p$-Pb collisions, a near side depression in the angular correlation is observed for low ${p}_{T}$ proton pairs and $\mathrm{\ensuremath{\Lambda}}$ pairs but not for pion pairs or kaon pairs, similar to our earlier finding for $pp$ collisions at $\sqrt{s}=7$ TeV. This is also the case for very low multiplicity Pb-Pb and Au-Au collisions. We also find that parton interactions and the improved quark coalescence are mainly responsible for the depression feature in baryon pair angular correlations. However, no such baryon-baryon anticorrelations are observed in Pb-Pb and Au-Au collisions at higher multiplicities. Therefore our results suggest that low ${p}_{T}$ baryon-baryon angular anticorrelations have a strong multiplicity dependence.
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Two-particle angular correlations in p p and p -Pb collisions at energies available at the CERN Large Hadron Collider from a Multiphase Transport model
Physical Review C, 2018Co-Authors: L. Y. Zhang, Ziwei Lin, Jinhui Chen, Song ZhangAbstract:We apply a Multiphase Transport (AMPT) model to study two-particle angular correlations in $pp$ collisions at $\sqrt{s}=7\phantom{\rule{0.16em}{0ex}}\mathrm{TeV}$. In addition to being able to describe the angular correlation functions of meson-meson pairs, a large improvement for the angular correlations of baryon-baryon and antibaryon-antibaryon is achieved. We further find that the AMPT model with new quark coalescence provides an even better description on the anticorrelation feature of baryon-baryon correlations observed in the experiments. We also extend the study to $p$-Pb collisions at $\sqrt{s}=5.02\phantom{\rule{0.16em}{0ex}}\mathrm{TeV}$ and obtained similar results. These results help us better understand the particle production mechanism in $pp$ and $p$-Pb collisions at Large Hadron Collider energies.
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Explore the QCD phase transition phenomena from a Multiphase Transport model
Science China Physics Mechanics & Astronomy, 2018Co-Authors: Xiao-hai Jin, Ziwei Lin, Jinhui Chen, G. L., Song ZhangAbstract:We study the phase structure of QCD matter in the framework of a Multiphase Transport model by implementing a strong local parton density fluctuation scenario. Our calculations on the beam energy dependence of net-proton high moment show that local parton density fluctuation only has a small effect. But it becomes important when all baryons are included. We then study the effect on elliptic flow and find that an enhanced local parton density fluctuation leads to a significant effect on protons but a small effect on pions. Our study provides a reference of Transport dynamics on QCD phase transition phenomena and will be relevant for the upcoming phase II of the beam energy scan program at RHIC.