期刊：
EUROPEAN PHYSICAL JOURNAL C,2024年84(9):1-12 ISSN：1434-6044
通讯作者：
Zhang, C
作者机构：
[Zhang, Chao; Zhang, C] Wuhan Univ Technol, Sch Sci, Dept Phys Sci & Technol, Wuhan 430070, Peoples R China.;[Shi, Shusu; Zhang, Chao; Zhang, C] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Zheng, Liang] China Univ Geosci Wuhan, Sch Math & Phys, Wuhan 430074, Peoples R China.;[Zhang, Chao; Zhang, C; Zheng, Liang] Shanghai Res Ctr Theoret Nucl Phys, NSFC, Shanghai 200438, Peoples R China.;[Zhang, Chao; Zhang, C; Zheng, Liang] Fudan Univ, Shanghai 200438, Peoples R China.
通讯机构：
[Zhang, C ] W;Wuhan Univ Technol, Sch Sci, Dept Phys Sci & Technol, Wuhan 430070, Peoples R China.;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;Shanghai Res Ctr Theoret Nucl Phys, NSFC, Shanghai 200438, Peoples R China.;Fudan Univ, Shanghai 200438, Peoples R China.
摘要：
We study the production of
$$D^0$$
meson in p+p and p-Pb collisions using the improved AMPT model considering both coalescence and independent fragmentation of charm quarks after the Cronin broadening is included. After a detailed discussion of the improvements implemented in the AMPT model for heavy quark production, we show that the modified AMPT model can provide a good description of
$$D^0$$
meson spectra in p-Pb collisions, the
$$Q_{\textrm{pPb}}$$
data at different centralities and
$$R_{\textrm{pPb}}$$
data in both mid- and forward (backward) rapidities. We also studied the effects of nuclear shadowing and parton cascade on the rapidity dependence of
$$D^{0}$$
meson production and
$$R_{\textrm{pPb}}$$
. Our results indicate that using the same strength of the Cronin effect (i.e
$$\delta $$
value) as that obtained from the mid-rapidity data leads to a considerable overestimation of the
$$D^0$$
meson spectra and
$$R_{\textrm{pPb}}$$
data at high
$$p_{\textrm{T}}$$
in the backward rapidity. As a result, the
$$\delta $$
is determined via a
$$\chi ^2$$
fitting of the
$$R_{\textrm{pPb}}$$
data across various rapidities. This work lays the foundation for a better understanding of cold-nuclear-matter (CNM) effects in relativistic heavy-ion collisions.
作者机构：
[Shi, Shusu; Liu, Zuo-Wen] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;Cent China Normal Univ, Inst Particle Phys, Wuhan, Peoples R China.
通讯机构：
[Shi, SS ] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.
摘要：
The E895 and STAR experiments demonstrate that the slopes of directed flow with respect to rapidity (dv1/dy|y=0) of mesons are negative in the low transverse momentum (pT ) region, pT <0.8 GeV/c, in Au + Au collisions at root sNN = 3.0-3.9 GeV. Using the transport model JAM, we investigate the directed flow of pi +/-, K +/-, and K0 as functions of rapidity, pT, and collision energy in Au + Au collisions at the same energies as those in the E895 and STAR experiments. We find that the JAM model can qualitatively reproduce the antiflow of KS0 observed in the E895 experiment. The v1 slopes of pions and kaons are analyzed as functions of the pT window, revealing a strong pT dependence of the v1 slopes. Negative v1 slopes are observed in the low pT region, pT <0.8 GeV/c, while positive slopes are shown in the higher pT region. We find that the shadowing effect from spectators is crucial in generating the antiflow of mesons at low pT in the high baryon density region.
作者机构：
[Nayak, Kishora] Sambalpur Univ, Panchayat Coll, Dept Phys, Bargarh 768028, India.;[Shi, Shu-Su] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Shi, Shu-Su] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Lin, Zi-Wei] East Carolina Univ, Dept Phys, Greenville, NC 27858 USA.
通讯机构：
[Nayak, K ] S;Sambalpur Univ, Panchayat Coll, Dept Phys, Bargarh 768028, India.
关键词：
directed flow;coalescence sum rule
摘要：
Recently, the rapidity-odd directed flow (v1) of produced hadrons (K-, phi, p over bar , Lambda over bar , Xi over bar +, omega-, and omega over bar +) has been studied. Several combinations of these produced hadrons, with very small mass differences but differences in the net electric charge (Delta q) and net strangeness (Delta S) on the two sides, have been considered. A difference in v1 between the two sides of these combinations (Delta v1) has been proposed as a consequence of the electromagnetic field produced in relativistic heavy-ion collisions, especially if Delta v1 increases with Delta q. Our study is performed to understand the effect of the coalescence sum rule (CSR) on Delta v1. We point out that the CSR leads to Delta v1=cq Delta q+cS Delta S, where the coefficients cq and cS reflect the Delta v1 of produced quarks. Equivalently, one can write Delta v1=cq Delta q+cB Delta B, involving the difference in the net baryon number Delta B, where the CSR gives cB=-3cS. We then propose two methods to extract the coefficients for the Delta q and Delta S dependences of Delta v1.
摘要：
The zero-degree calorimeter (ZDC) plays a crucial role toward determining the centrality in the Cooling-Storage-Ring External-target Experiment (CEE) at the Heavy Ion Research Facility in Lanzhou. A boosted decision tree (BDT) multi-classification algorithm was employed to classify the centrality of the collision events based on the raw features from ZDC such as the number of fired channels and deposited energy. The data from simulated
$$^{238}\textrm{U}$$
+
$$^{238}\textrm{U}$$
collisions at 500
$$\mathrm{MeV/u}$$
, generated by the IQMD event generator and subsequently modeled using the GEANT4 package, were employed to train and test the BDT model. The results showed the high accuracy of the multi-classification model adopted in ZDC for centrality determination, which is robust against variations in different factors of detector geometry and response. This study demonstrates the good performance of CEE-ZDC in determining the centrality in nucleus–nucleus collisions.
作者机构：
[Huang, Huan Zhong] Univ Calif Los Angeles, Dept Phys & Astrophys, Los Angeles, CA 90095 USA.;[Shi, Shusu; Luo, Xiaofeng; Liu, Feng] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Shi, Shusu; Luo, Xiaofeng; Liu, Feng] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Wang, Fuqiang] Purdue Univ, Dept Phys, W Lafayette, IN 47907 USA.;[Xu, Nu] Lawrence Berkeley Natl Lab, Nucl Sci Div, Berkeley, CA 94720 USA.
通讯机构：
[Shusu Shi] K;Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
high-energy nuclear collisions;collectivity;chirality;criticality;QCD;critical point;phase boundary;strangeness;thermalization;viscosity;baryon density
摘要：
<jats:p>We celebrate the legacies of our friend and mentor Professor Lianshou Liu who was one of the pioneers for the phenomenology of multi-particle interactions and initiated the physics of relativistic heavy-ion collisions in China. In this article, we discuss some of the recent exciting experimental observations on the collective phenomena including collectivity, chirality, criticality, strangeness production, and thermal equilibrium in high-energy nuclear collisions. Future directions, especially the physics at high baryon density, will be discussed with a focus on the first-order phase boundary and hyperon–nucleon interactions.</jats:p>
摘要：
本文讨论了RHIC-STAR相对论重离子碰撞实验近年来重要的结果.主要包括高能重离子碰撞中夸克物质的集体运动性质和能量扫描实验中各阶集体流的研究,守恒荷的高阶矩与强相互作用相变临界点的探索,以及重味、奇异粒子和轻核产生的测量.我们发现STAR实验最高能量的重离子碰撞中形成了热化的夸克物质,多个信号表明当碰撞能量低于39 Ge V之时,可能进入了强相互作用相图的临界区.最后对未来重离子碰撞实验的运行计划和研究重点做了展望.
作者机构：
[Zhang, Biao; Wang, Ya-Ping; Pei, Hua; Xu, Nu; Shi, Shu-Su; Liu, Li-Ke] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Zhang, Biao; Wang, Ya-Ping; Pei, Hua; Xu, Nu; Shi, Shu-Su; Liu, Li-Ke] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Shi, SS ] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
摘要：
The Cooling Storage Ring external-target experiment (CEE) spectrometer is used to study the nuclear matter created in heavy-ion collisions at
$$\sqrt{s_{_{\mathrm{{NN}}}}}$$
= 2.1–2.4GeV with the aim to reveal the quantum chromodynamics phase structure in the high-baryon-density region. Collective flow is considered an effective probe for evaluating the properties of media during high-energy nuclear collisions. One of the main functions of the zero-degree calorimeter (ZDC), a subdetector system in the CEE, is to determine the reaction plane in heavy-ion collisions. This step is crucial for measuring the collective flow and other reaction-plane-related analyses. In this paper, we illustrate the procedures for event plane determination using the ZDC. Finally, isospin-dependent quantum molecular dynamics model-based predictions of the rapidity dependence of the directed and elliptical flows for p, d, t,
$$^3$$
He, and
$$^4$$
He, produced in 2.1 GeV U+U collisions, are presented.
摘要：
It has been a challenge to understand the experimental data on both the nuclear modification factor and elliptic flow of D0 mesons in p-Pb collisions at LHC energies. In this work, we study these collisions with an improved multi-phase transport model. By including the independent fragmentation and a significant Cronin effect (i.e., transverse momentum broadening) for charm quarks, we provide the first simultaneous description of the D0 meson RpA and v2 data at pT <= 8 GeV/c. The model also reasonably describes the D0 meson pT spectra and the low-pT charged hadron spectra, RpA and v2. Our results show that both parton interactions and the Cronin effect are important for the D0 meson RpA, while parton interactions are mostly responsible for the D0 meson v2. It is thus essential to include the Cronin effect for the simultaneous description of the D0 meson RpA and v2. This work implies that the Cronin effect could also be important for heavy hadrons in large systems. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3.
摘要：
Collective flow is a powerful tool used to analyze the properties of a medium created during high-energy nuclear collisions. Here, we report a systematic study of the first two Fourier coefficients
$$v_1$$
and
$$v_2$$
of the proton and
$$\pi ^{+}$$
from Au+Au collisions in the energy range
$$\sqrt{s_{{\text{NN}}}}$$
= 2.11–4.9 GeV within the framework of a hadronic transport model (UrQMD). Recent results from the STAR experiment were used to test the model calculations. A mean-field mode with strong repulsive interaction is needed to reproduce the 10–40% data at 3 GeV. This implies that hadronic interactions play an important role in the collective flow development in the high baryon density region. The mean values of the freeze-out time for protons and
$$\pi ^{+}$$
are shifted earlier owing to the additional repulsive interactions. We predict the energy dependence of the mean values of the transverse momentum
$$\langle p_{\text{T}} \rangle$$
,
$$v_1$$
, and
$$v_2$$
for both protons and
$$\pi ^{+}$$
from the Au+Au collisions.
作者：
Agakishiev, H.*;Aggarwal, M. M.;Ahammed, Z.;Alakhverdyants, A., V;Alekseev, I;...
期刊：
中国物理C,2021年45(4):198-241 ISSN：1674-1137
通讯作者：
Agakishiev, H.
作者机构：
[Kechechyan, A.; Agakishiev, H.; Averichev, G. S.; Efimov, L. G.; Alakhverdyants, A., V; Kizka, V; Rogachevskiy, O., V; Panebratsev, Y.; Shahaliev, E.; Fedorisin, J.; Bunzarov, I; Zoulkarneev, R.; Zoulkarneeva, Y.; Tokarev, M.; Filip, P.; Lednicky, R.; Dedovich, T. G.; Vokal, S.] Joint Inst Nucl Res, Dubna 141980, Russia.;[Underwood, D. G.; Krueger, K.; Bridgeman, A.; Spinka, H. M.] Argonne Natl Lab, Argonne, IL 60439 USA.;[Ullrich, T.; Pile, P.; Lamont, M. A. C.; Ljubicic, T.; Le Vine, M. J.; Xu, Z.; Ogawa, A.; Ruan, L.; Tang, A. H.; Videbaek, F.; Fisyak, Y.; Beavis, D. R.; Lauret, J.; Bland, L. C.; Longacre, R. S.; Webb, J. C.; Christie, W.; Arkhipkin, D.; Fine, V; Debbe, R. R.; Lebedev, A.; Burton, T. P.; Dunlop, J. C.; Gordon, A.; Landgraf, J. M.; Love, W. A.; Yip, K.; Didenko, L.; Guryn, W.; Van Buren, G.; Lee, J. H.] Brookhaven Natl Lab, Upton, NY 11973 USA.;[Perkins, C.; Crawford, H. J.; Engelage, J.; Judd, E. G.] Univ Calif Berkeley, Berkeley, CA 94720 USA.;[Sanchez, M. Calderon de la Barca; Draper, J. E.; Cebra, D.; Brovko, S. G.; Mall, O., I; Sangaline, E.; Reed, R.; Romero, J. L.; Salur, S.; Haag, B.; Liu, H.] Univ Calif Davis, Davis, CA 95616 USA.
通讯机构：
[Agakishiev, H.] J;Joint Inst Nucl Res, Dubna 141980, Russia.
关键词：
relativistic heavy ion collisions;dihadron correlations;jet-medium interactions;anisotropic flow background;event plane
摘要：
<jats:title>Abstract</jats:title>
<jats:p>Dihadron azimuthal correlations containing a high transverse momentum (
<jats:inline-formula>
<jats:tex-math><?CDATA $ p_{T} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M2.jpg" xlink:type="simple" />
</jats:inline-formula>) trigger particle are sensitive to the properties of the nuclear medium created at RHIC through the strong interactions occurring between the traversing parton and the medium, i.e. jet-quenching. Previous measurements revealed a strong modification to dihadron azimuthal correlations in Au+Au collisions with respect to <jats:italic>p</jats:italic>+<jats:italic>p</jats:italic> and <jats:italic>d</jats:italic>+Au collisions. The modification increases with the collision centrality, suggesting a path-length or energy density dependence to the jet-quenching effect. This paper reports STAR measurements of dihadron azimuthal correlations in mid-central (20%-60%) Au+Au collisions at
<jats:inline-formula>
<jats:tex-math><?CDATA $ \sqrt{s_{\rm{NN}}} = 200 $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M3.jpg" xlink:type="simple" />
</jats:inline-formula> GeV as a function of the trigger particle's azimuthal angle relative to the event plane,
<jats:inline-formula>
<jats:tex-math><?CDATA $ \phi_{s} = | \phi_{t}- \psi_{{\rm{EP}}}| $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M4.jpg" xlink:type="simple" />
</jats:inline-formula>. The azimuthal correlation is studied as a function of both the trigger and associated particle
<jats:inline-formula>
<jats:tex-math><?CDATA $ p_{T} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M5.jpg" xlink:type="simple" />
</jats:inline-formula>. The subtractions of the combinatorial background and anisotropic flow, assuming Zero Yield At Minimum (ZYAM), are described. The correlation results are first discussed with subtraction of the even harmonic (elliptic and quadrangular) flow backgrounds. The away-side correlation is strongly modified, and the modification varies with
<jats:inline-formula>
<jats:tex-math><?CDATA $ \phi_{s} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M6.jpg" xlink:type="simple" />
</jats:inline-formula>, with a double-peak structure for out-of-plane trigger particles. The near-side ridge (long range pseudo-rapidity
<jats:inline-formula>
<jats:tex-math><?CDATA $ \Delta\eta $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M7.jpg" xlink:type="simple" />
</jats:inline-formula> correlation) appears to drop with increasing
<jats:inline-formula>
<jats:tex-math><?CDATA $ \phi_{s} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M8.jpg" xlink:type="simple" />
</jats:inline-formula> while the jet-like component remains approximately constant. The correlation functions are further studied with the subtraction of odd harmonic triangular flow background arising from fluctuations. It is found that the triangular flow, while responsible for the majority of the amplitudes, is not sufficient to explain the
<jats:inline-formula>
<jats:tex-math><?CDATA $ \phi_{s} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M9.jpg" xlink:type="simple" />
</jats:inline-formula>-dependence of the ridge or the away-side double-peak structure. The dropping ridge with
<jats:inline-formula>
<jats:tex-math><?CDATA $ \phi_{s} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M10.jpg" xlink:type="simple" />
</jats:inline-formula> could be attributed to a
<jats:inline-formula>
<jats:tex-math><?CDATA $ \phi_{s} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M11.jpg" xlink:type="simple" />
</jats:inline-formula>-dependent elliptic anisotropy; however, the physics mechanism of the ridge remains an open question. Even with a
<jats:inline-formula>
<jats:tex-math><?CDATA $ \phi_{s} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M12.jpg" xlink:type="simple" />
</jats:inline-formula>-dependent elliptic flow, the away-side correlation structure is robust. These results, with extensive systematic studies of the dihadron correlations as a function of
<jats:inline-formula>
<jats:tex-math><?CDATA $ \phi_{s} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M13.jpg" xlink:type="simple" />
</jats:inline-formula>, trigger and associated particle
<jats:inline-formula>
<jats:tex-math><?CDATA $ p_{T} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M14.jpg" xlink:type="simple" />
</jats:inline-formula>, and the pseudo-rapidity range
<jats:inline-formula>
<jats:tex-math><?CDATA $ \Delta\eta $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_4_044002_M15.jpg" xlink:type="simple" />
</jats:inline-formula>, should provide stringent inputs to help understand the underlying physics mechanisms of jet-medium interactions in high energy nuclear collisions.
</jats:p>
作者机构：
[Shi, Shusu; Zhang, Chao] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Shi, Shusu; Zhang, Chao] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Zhang, Chao; Lin, Zi-Wei] East Carolina Univ, Dept Phys, Greenville, NC 27858 USA.;[Zheng, Liang] China Univ Geosci Wuhan, Sch Math & Phys, Wuhan 430074, Peoples R China.
摘要：
We extensively study the system size dependence of nuclear collisions with a multiphase transport model. Previously, certain key parameters for the initial condition needed significantly different values for pp and central AA collisions for the model to reasonably describe the yields and transverse momentum spectra of the bulk matter in those collision systems. Here we scale two key parameters, the Lund string fragmentation parameter bL and the minijet transverse momentum cutoff p0 , with local nuclear thickness functions from the two colliding nuclei. This allows the model to use the parameter values for pp collisions with the local nuclear scaling to describe the system size and centrality dependences of nuclear collisions self-consistently. In addition to providing good descriptions of pp collisions from 23.6 GeV to 13 TeV and reasonable descriptions of the centrality dependence of charged particle yields for Au+Au collisions from 7.7A GeV to 200A GeV and Pb+Pb collisions at Large Hadron Collider energies, the improved model can now well describe the centrality dependence of the mean transverse momentum of charged particles below pT≲2 GeV. It works similarly well for smaller systems including pPb , Cu+Cu and Xe+Xe collisions.
作者机构：
[Zheng, L.] China Univ Geosci Wuhan, Sch Math & Phys, Wuhan 430074, Peoples R China.;[Zhang, C.; Shi, S. S.; Zheng, L.; Lin, Z. W.] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Zhang, C.; Shi, S. S.; Zheng, L.; Lin, Z. W.] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Lin, Z. W.] East Carolina Univ, Dept Phys, Greenville, NC 27858 USA.
通讯机构：
[Zheng, L.] C;China Univ Geosci Wuhan, Sch Math & Phys, Wuhan 430074, Peoples R China.;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
摘要：
Recently we updated a multiphase transport (ampt) model with modern parton distribution functions of nuclei (nPDFs). Here we study open charm production in the updated ampt model and compare to the experimental data from pp and AA collisions over a wide range of collision energies. Besides the update of nPDFs, we removed the transverse momentum cutoff on initial heavy quark productions and also included the resultant heavy flavor cross section into the total minijet cross section in the initial condition as described by the hijing model. We show that the ampt model with these updates provides a much better description of the yields and transverse momentum spectra of various open charm hadrons in comparison with the experimental data. This lays the foundation for further heavy flavor studies within the transport model approach.
作者机构：
[Shi, Shusu; Xu, Nu; Lin, Zi-Wei; Nayak, Kishora] Cent China Normal Univ, Key Lab Quark & Lepton Phys, MOE, Wuhan 430079, Hubei, Peoples R China.;[Shi, Shusu; Xu, Nu; Lin, Zi-Wei; Nayak, Kishora] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;[Xu, Nu] Chinese Acad Sci, Inst Modern Phys, Lanzhou, Gansu, Peoples R China.;[Lin, Zi-Wei] East Carolina Univ, Dept Phys, Greenville, NC 27858 USA.
通讯机构：
[Shi, Shusu] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys, MOE, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.
摘要：
The rapidity-odd component of directed flow ( v1) of identified hadrons ( π±, K±, KS0, p, p¯, ϕ, Ξ, Ξ¯, Λ, Λ¯) and partons ( u, u¯, d, d¯, s, s¯) in Au+Au collisions at various beam energies ( sNN=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 ϕ meson slope ( dv1/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.
作者机构：
[Shi, Shusu] Cent China Normal Univ, Key Lab Quarks & Lepton Phys, MOE, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.
通讯机构：
[Shi, Shusu] C;Cent China Normal Univ, Key Lab Quarks & Lepton Phys, MOE, Wuhan 430079, Hubei, Peoples R China.
关键词：
elliptic flow;UrQMD;beam energy scan
摘要：
<jats:title>Abstract</jats:title>
<jats:p>Within the framework of the UrQMD model, by tracing the number of initial quarks in protons, we study the elliptic flow of protons with 3, 2, 1, 0 initial quarks and anti-protons in Au+Au collisions at
<jats:inline-formula>
<jats:tex-math><?CDATA $ \sqrt{s_{{\rm NN}}} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_43_5_054106_M1.jpg" xlink:type="simple" />
</jats:inline-formula> = 7.7, 11.5, 39, 200 GeV. The difference of elliptic flow between protons with 2, 1, 0 initial quarks and anti-protons is smaller than 0, or consistent with 0, respectively. The difference of elliptic flow between transported protons (with 3 initial quarks) and anti-protons is larger than 0 at 7.7, 11.5 and 39 GeV. This is in good agreement with the STAR results at 7.7 and 11.5 GeV, but overestimates the STAR results at 39 GeV. The yield of transported protons with 3 initial quarks is smaller than of protons with 2 and 1 initial quarks, and
<jats:inline-formula>
<jats:tex-math><?CDATA $ v_{2} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_43_5_054106_M2.jpg" xlink:type="simple" />
</jats:inline-formula> of all protons is much smaller than the STAR results. The observation of the difference of elliptic flow between transported protons and anti-protons in the UrQMD model partly explains the
<jats:inline-formula>
<jats:tex-math><?CDATA $ v_{2} $?></jats:tex-math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_43_5_054106_M3.jpg" xlink:type="simple" />
</jats:inline-formula> difference between protons and anti-protons observed in the Beam Energy Scan program at the Relativistic Heavy Ion Collider (RHIC).
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作者机构：
[Zhang, Chao; Zheng, Liang; Liu, Feng; Shi, Shusu; Lin, Zi-Wei] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China;[Zhang, Chao; Zheng, Liang; Liu, Feng; Shi, Shusu; Lin, Zi-Wei] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China;[Zheng, Liang] China Univ Geosci, Wuhan 430074, Hubei, Peoples R China;[Lin, Zi-Wei] East Carolina Univ, Dept Phys, Greenville, NC 27858 USA
通讯机构：
[Shi, Shusu] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China. Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.
摘要：
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 pp¯ total and inelastic cross sections from s∼ 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 high−pT 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.
作者机构：
[Shi, Shusu; Sun, Xu; Lin, Zi-Wei; Lan, Shaowei] Cent China Normal Univ, MOE, Key Lab Quarks & Lepton Phys, Wuhan 430079, Hubei, Peoples R China.;[Shi, Shusu; Sun, Xu; Lin, Zi-Wei; Lan, Shaowei] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;[Lin, Zi-Wei] East Carolina Univ, Dept Phys, Greenville, NC 27858 USA.
通讯机构：
[Shi, Shusu] C;Cent China Normal Univ, MOE, Key Lab Quarks & Lepton Phys, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.
摘要：
In non-central relativistic heavy ion collisions, the created matter possesses a large initial orbital angular momentum. Particles produced in the collisions could be polarized globally in the direction of the orbital angular momentum due to spin-orbit coupling. Recently, the STAR experiment has presented polarization signals for A hyperons and possible spin alignment signals for empty set mesons. Here we discuss the effects of finite coverage on these observables. The results from a multi-phase transport and a toy model both indicate that a pseudorapidity coverage narrower than vertical bar eta vertical bar <similar to 1 will generate a larger value for the extracted empty set-meson rho(00) parameter; thus a finite coverage can lead to an artificial deviation of rho(00) from 1/3. We also show that a finite eta and p(T) . coverage affect the extracted p(H) parameter for Lambda hyperons when the real p(H) value is non-zero. Therefore proper corrections are necessary to reliably quantify the global polarization with experimental observables. (C) 2018 The Author(s). Published by Elsevier B.V.
摘要：
Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (
$\sqrt{s_{NN}}=$
2.7--4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (
$\mu_B > 500$
MeV), effects of chiral symmetry, and the equation of state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2024, in the context of the worldwide efforts to explore high-density QCD matter.
期刊：
Journal of Physics: Conference Series,2017年779(1):012008 ISSN：1742-6588
通讯作者：
Shi, Shusu
作者机构：
[Shi, Shusu] Cent China Normal Univ, Key Lab Quarks & Lepton Phys MOE, Wuhan 430079, Peoples R China.;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Shi, Shusu] C;Cent China Normal Univ, Key Lab Quarks & Lepton Phys MOE, Wuhan 430079, Peoples R China.
会议名称：
16th International Conference on Strangeness in Quark Matter (SQM)
期刊：
Advances in High Energy Physics,2016年2016:1-9 ISSN：1687-7357
通讯作者：
Shi, Shusu
作者机构：
[Shi, Shusu] Cent China Normal Univ, Key Lab Quarks & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Shi, Shusu] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Shi, Shusu] C;Cent China Normal Univ, Key Lab Quarks & Lepton Phys MOE, Wuhan 430079, Peoples R China.;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
