作者机构：
[Li, Zhiming] 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.
通讯机构：
[Li, Zhiming] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.
摘要：
It is shown that intermittency, a self-similar correlation with respect to the size of the phase space volume, is sensitive to critical density fluctuations of baryon numbers in a system belonging to the three-dimensional (3D) Ising universality class. The relation between intermittency index and relative baryon density fluctuation is obtained. We thus suggest that measuring the intermittency in relativistic heavy-ion collisions could be used as a good probe of density fluctuations associated with the QCD critical phenomena. From recent preliminary results on neutron density fluctuations in central Au + Au collisions at root s(NN) = 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV at RHIC/STAR, the collision energy dependence of intermittency index is extracted and shows a non-monotonic behavior with a peak at around 20 - 27 GeV, indicating that the strength of intermittency becomes the largest in this energy region. The transport UrQMD model without implementing critical physics cannot describe the observed behavior. (C) 2019 The Authors. Published by Elsevier B.V.
作者机构：
[Zhang, Yanhua; Zhao, Yeyin; Wu, Yuanfang; Xu, Mingmei; Li, Zhiming] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.;[Zhang, Yanhua; Zhao, Yeyin; Wu, Yuanfang; Xu, Mingmei; Li, Zhiming] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;[Chen, Lizhu] Nanjing Univ Informat Sci & Technol, Sch Phys & Optoelect Engn, Nanjing 210044, Jiangsu, Peoples R China.;[Pan, Xue] Chengdu Technol Univ, Sch Elect Engn, Chengdu 611730, Sichuan, Peoples R China.;[Zhou, Yu] Cent China Normal Univ, 1 Middle Sch, Wuhan 430223, Hubei, Peoples R China.
通讯机构：
[Wu, Yuanfang] 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 critical point is a fixed point in finite-size scaling. To quantify the behavior of such a fixed point, we define, at a given temperature and scaling exponent ratio, the width of scaled observables for different sizes. The minimum of the width reveals the position of the fixed point, its corresponding phase transition temperature, and scaling exponent ratio. The value of this ratio tells the nature of the fixed point, which can be a critical point, a point of the first-order phase transition line, or a point of the crossover region. To demonstrate the effectiveness of this method, we apply it to three typical samples produced by the three-dimensional three-state Potts model. Results show the method to be more precise and effective than conventional methods. Finally, we discuss a possible application at the Beam Energy Scan program of the Relativistic Heavy Ion Collider.
作者机构：
[Zhang, Donghai; Zhao, Yeyin; Zhang, Hengying; Wu, Yuanfang; Xu, Mingmei; Xu, MM] Cent China Normal Univ, MOE, Key Lab Quark & Lepton Phys, Wuhan 430079, Hubei, Peoples R China.;[Zhang, Donghai; Zhao, Yeyin; Zhang, Hengying; Wu, Yuanfang; Xu, Mingmei; Xu, MM] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;[Pan, Xue] Chengdu Technol Univ, Sch Elect Engn, Chengdu 611730, Sichuan, Peoples R China.
通讯机构：
[Xu, MM; Wu, YF] C;Cent China Normal Univ, MOE, Key Lab Quark & Lepton Phys, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.
摘要：
We investigate the azimuthal correlations of the glasma in p-p collisions at sNN=7 TeV by using the color glass condensate (CGC) formalism. As expected, the azimuthal correlations show two peaks at Δϕ=0 and π, which represent collimation production in the CGC. Beyond that, azimuthal correlations show fine structures, i.e., bumps or shoulders between the two peaks, when at least one gluon has small x. The structures are demonstrated to be associated with saturation momentum and likely appear at transverse momentum around 2Qsp=1.8 GeV/c.
摘要：
Taking doubly charged particles, positive-negative charge pair production and the effects of volume fluctuations into account, the Poisson baseline of the fluctuations of net-charge is studied. Within the Poisson baseline, the cumulants of net-charge are derived. Comparing to the Skellam baseline of net-charge, we infer that doubly charged particles broaden the distributions of net-charge, while positive-negative charge pairs narrow the distributions. Using the ratios of doubly charged particles and positive-negative charge pairs from neutral resonance decays to the total positive charges from THERMINATOR 2, the first four orders of moments and the corresponding moment products are calculated in the Poisson baseline for Au + Au collisions at (S_(NN))~(1/2)= 200 GeV at RHIC/STAR. We find that the standard deviation is mainly influenced by the resonance decay, while the third and fourth order moments and corresponding moment products are mainly modified and fit the data of RHIC/STAR much better after including the effects of volume fluctuations.
关键词：
High cumulants;statistical uncertainty;statistics;QCD phase transition
摘要：
We study the influence of measured high cumulants of conserved charges on their associated statistical uncertainties in relativistic heavy-ion collisions. With a given number of events, the measured cumulants randomly fluctuate with an approximately normal distribution, while the estimated statistical uncertainties are found to be correlated with corresponding values of the obtained cumulants. Generally, with a given number of events, the larger the cumulants we measure, the larger the statistical uncertainties that are estimated. The error-weighted averaged cumulants are dependent on statistics. Despite this effect, however, it is found that the three sigma rule of thumb is still applicable when the statistics are above one million.
作者机构：
[Chen, Lizhu; Cui, Fenping] Nanjing Univ Informat Sci & Technol, Sch Phys & Optoelect Engn, Nanjing 210044, Jiangsu, Peoples R China.;[Chen, Lizhu; Wu, Yuanfang; Li, Zhiming] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Chen, Lizhu; Wu, Yuanfang; Li, Zhiming] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Chen, Lizhu] N;[Chen, Lizhu] C;Nanjing Univ Informat Sci & Technol, Sch Phys & Optoelect Engn, Nanjing 210044, Jiangsu, 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.
关键词：
The sixth order cumulant;Statistics;Non-critical contributions;Heavy-ion collisions
摘要：
We investigate the measurement of the sixth order cumulant and its ratio to the second order cumulant (C-6/C-2) in relativistic heavy-ion collisions. The influence of statistics and different methods of centrality bin width correction on C-6/C-2 of net-proton multiplicity distributions is demonstrated. There is no satisfactory method to extract C-6/C-2 with the current statistics recorded at lower energies by STAR at RHIC. With statistics comparable to the expected statistics at the planned future RHIC Beam Energy Scan II (BES II), no energy dependence of C-6/C-2 is observed in central collisions using the UrQMD model. We find that if the transition signal is as strong as predicted by the PQM model, then it is hopefully observed at the upcoming RHIC BES II. (C) 2016 Elsevier B.V. All rights reserved.
摘要：
Using a multi-phase transport model (AMPT) that includes both initial partonic and hadronic interactions, we study neighboring bin multiplicity correlations as a function of pseudorapidity in Au+Au collisions at √SNN = 7.7 — 62.4 GeV. It is observed that for √SNN <19.6 GeV Au+Au collisions, the short-range correlations of final particles have a trough at central pseudorapidity, while for √SNN >19.6 GeV AuAu collisions,the short-range correlations of final particles have a peak at central pseudorapidity. Our findings indicate that the pseudorapidity dependence of short-range correlations should contain some new physical information, and are not a simple result of the pseudorapidity distribution of final particles. The AMPT results with and without hadronic scattering are compared. It is found that hadron scattering can only increase the short-range correlations to some level, but is not responsible for the different correlation shapes for different energies. Further study shows that the different pseudorapidity dependence of short-range correlations are mainly due to partonic evolution and the following hadronization scheme.
关键词：
critical point;the sixth order cumulant;Ising model
摘要：
The high-order cumulants of conserved charges are suggested to be sensitive observables to search for the critical point of Quantum Chromodynamics (QCD). This has been calculated to the sixth order in experiments. Corresponding theoretical studies on the sixth order cumulant are necessary. Based on the universality of the critical behavior, we study the temperature dependence of the sixth order cumulant of the order parameter using the parametric representation of the three-dimensional Ising model, which is expected to be in the same universality class as QCD. The density plot of the sign of the sixth order cumulant is shown on the temperature and external magnetic field plane. We found that at non-zero external magnetic field, when the critical point is approached from the crossover side, the sixth order cumulant has a negative valley. The width of the negative valley narrows with decreasing external field. Qualitatively, the trend is similar to the result of Monte Carlo simulation on a finite-size system. Quantitatively, the temperature of the sign change is different. Through Monte Carlo simulation of the Ising model, we calculated the sixth order cumulant of different sizes of systems. We discuss the finite-size effects on the temperature at which the cumulant changes sign.
作者机构：
[Wu, Yuan-Fang] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Wu, Yuan-Fang] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Wu, Yuan-Fang] 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：
Using the CGC formalism, we calculate the two-gluon rapidity correlations of strong colour fields in pp, pA and AA collisions, respectively. If one trigger gluon is fixed at central rapidity, a ridge-like correlation pattern is obtained in symmetry pp and AA collisions, and a huge bump-like correlation pattern is presented in asymmetry pA collisions. It is demonstrated that long-range ridge-like rapidity correlations are caused by the stronger correlation with the gluon of colour source. These features are independent of the azimuthal angular of two selected gluon. They are qualitatively consistent with current observed data at LHC. The transverse momentum and incident energy dependence of the ridge and bump-like correlations are also systematically studied. The ridge is more likely observed at higher incident energy and lower transverse momentum of trigger gluon. (C) 2016 Elsevier B.V. All rights reserved.
期刊：
JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS,2015年42(1):015104- ISSN：0954-3899
通讯作者：
Pan, Xue
作者机构：
[Pan, Xue] 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.
通讯机构：
[Pan, Xue] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.
关键词：
Finite-size scaling;Generalized susceptibility;QCD phase transition;Three-dimensional three-state potts model
摘要：
It is pointed out that the finite-size effect is not negligible in locating the critical point of quantum colordynamics (QCD) phase transitions at current relativistic heavy ion collisions. The finite-size scaling form of the critical related observable is suggested. Its fixed point behavior at critical incident energy can be served as a reliable identification of a critical point and nearby boundary of QCD phase transition. How to experimentally find the fixed point behavior is demonstrated by using 3D-Ising model as an example. The validity of the method at finite detector acceptances at RHIC is also discussed.
作者机构：
[Xu, Mingmei] 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.
通讯机构：
[Xu, Mingmei] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.
关键词：
Heavy ion collisions;Quark deconfinement;QCD critical point;Inflection point;High cumulant
摘要：
In the universality class of the critical point of QCD, the appearance of the inflection point in the equation of state (EoS) is associated with the second order phase transition. The high cumulants of conserved quantities near the critical point are corresponding to the high derivatives of the EoS near the inflection point. The critical behavior of high cumulants of conserved charge near the QCD critical point, in particular, the sign change, is closely related to the appearance of inflection point. We show in general how the times of sign change of high cumulants relate to the order of derivative. We also demonstrate that the character of inflection point of EoS is as visible as the sign change of high cumulants in 3 systems, i.e., the van der Waals equation of fluid, the energy of spin model and the baryon number density of QCD matter. Therefore, we propose that the EoS, or the mean of baryon number density, should be measured and studied together with its higher cumulants in exploring the QCD critical point in heavy ion collisions. (C) 2014 Elsevier B.V. All rights reserved.
作者机构：
[Wu, Yuanfang; Xu, Mingmei; Pan, Xue; Zhang, Fan; Li, Zhiming] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Wu, Yuanfang; Xu, Mingmei; Pan, Xue; Zhang, Fan; Li, Zhiming] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Chen, Lizhu] Nanjing Univ Informat Sci & Technol, Sch Phys & Optoelect Engn, Nanjing 210044, Jiangsu, Peoples R China.
通讯机构：
[Pan, Xue] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.
摘要：
Poisson-like statistical fluctuations, which are caused by the finite number of produced particles, are estimated for the cumulants of conserved charges, i.e., net baryon, net electric, and net strangeness. They turn out to be the same as those baselines derived from the hadron resonance gas model. The energy and centrality dependence of net-proton cumulants at the Relativistic Heavy-Ion Collider (RHIC) are demonstrated to be mainly caused by statistical fluctuations. By subtracting the statistical fluctuations, the dynamical kurtosis of net- and total-proton cumulants from two versions of a multi-phase transport model and the ultra-relativistic quantum molecular dynamics model at current RHIC collision energies are presented. It is found that the observed sign change of the dynamical kurtosis of the net-proton cumulant cannot be reproduced by these three transport models. There is no significant difference between the net- and total-proton kurtosis in model calculations, in contrast to the data at RHIC.
作者：
Agakishiev, H.*;Aggarwal, M. M.;Ahammed, Z.;Alakhverdyants, A. V.;Alekseev, I.;...
期刊：
PHYSICAL REVIEW C,2014年89(4) ISSN：2469-9985
通讯作者：
Agakishiev, H.
作者机构：
[Kechechyan, A.; Kizka, V.; Agakishiev, H.; Averichev, G. S.; Bunzarov, I.; Efimov, L. G.; Panebratsev, Y.; Alakhverdyants, A. V.; Shahaliev, E.; Rogachevskiy, O. V.; Fedorisin, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Tokarev, M.; Filip, P.; Lednicky, R.; Dedovich, T. G.; Heppelmann, S.; 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.; LeVine, M. J.; Ljubicic, T.; Xu, Z.; Ogawa, A.; Ruan, L.; Tang, A. H.; Videbaek, F.; Fine, V.; Fisyak, Y.; Beavis, D. R.; Lauret, J.; Bland, L. C.; Longacre, R. S.; Webb, J. C.; Christie, W.; Arkhipkin, D.; 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.; Alford, J.; Judd, E. G.] Univ Calif Berkeley, Berkeley, CA 94720 USA.;[Draper, J. E.; Cebra, D.; Brovko, S. G.; Beavis, D. R.; Sangaline, E.; Reed, R.; de la Barca Sanchez, M. Calderon; Romero, J. L.; Salur, S.; Haag, B.] Univ Calif Davis, Davis, CA 95616 USA.
通讯机构：
[Agakishiev, H.] J;Joint Inst Nucl Res, Dubna 141980, Russia.
摘要：
STAR measurements of dihadron azimuthal correlations (Lambda phi) are reported in midcentral (20-60%) Au + Au collisions at v root sNN = 200 GeV as a function of the trigger particle's azimuthal angle relative to the event plane, phi(s) = | phi(1) -psi(EP)|. The elliptic (v(2)), triangular (v(3)), and quadratic (v(4)) flow harmonic backgrounds are subtracted using the zero yield at mini + Au collisions. It is found that a finite near-side (| Delta phi | < pi/2) long-range pseudorapidity correlation (ridge) is present in the in-plane direction (phi(s) similar to 0). The away-side (| Delta phi | > pi/2) correlation shows a modification from d+ Au data, varying with fs. The modification may be a consequence of path-length-dependent jet quenching and may lead to a better understanding of high-density QCD.
摘要：
Considering different universality classes of the QCD phase transitions, we perform the Monte Carlo simulations of the 3-dimensional O(1, 2, 4) models at vanishing and non-vanishing external field, respectively. Interesting high-order cumulants of the order parameter and energy from O(1) (Ising) spin model, and the cumulants of the energy from O(2) and O(4) spin models are presented. The generic features of the cumulants are discussed. They are instructive to the high-order cumulants of the net baryon number in the QCD phase transitions. (C) 2013 Elsevier B.V. All rights reserved.
作者机构：
[Wu Yuan-Fang; Li Lin] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Wu Yuan-Fang; Li Lin] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Wang Mei-Juan] China Univ Geosci, Dept Phys, Wuhan 430074, Peoples R China.
通讯机构：
[Li Lin] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.
关键词：
neighboring azimuthal bin-bin multiplicity correlation;shear viscosity;relativistic heavy ion collision
摘要：
Neighboring azimuthal bin-bin multiplicity correlation is suggested to be a good measure for internal layer-to-layer interactions of the formed matter in relativistic heavy ion collisions. It is shown to be directly related to the shear viscosity of the formed matter. As an application of this method, the shear viscosity in the samples generated by a multi-phase transport model (AMPT) is estimated. The results are in qualitative agreement with the theoretical calculation from microscopic interactions, i.e., the larger the scattering cross section, the smaller the shear viscosity.
