作者机构:
[Luo, Xiaofeng; Liu, Feng; Zhou, Chang; Xu, Ji] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Luo, Xiaofeng; Liu, Feng; Zhou, Chang; Xu, Ji] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Luo, Xiaofeng] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA.
通讯机构:
[Luo, Xiaofeng] C;[Luo, Xiaofeng] U;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.;Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA.
摘要:
Fluctuations of conserved quantities, such as baryon, electric charge, and strangeness number, are sensitive observables in heavy-ion collisions to search for the QCD phase transition and critical point. In this paper, we performed a systematical analysis on the various cumulants and cumulant ratios of event-by-event net-strangeness distributions in Au+Au collisions at sNN=7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV from an ultrarelativistic quantum molecular dynamics model. We performed a systematical study on the contributions from various strange baryons and mesons to the net-strangeness fluctuations. The results demonstrate that the cumulants and cumulant ratios of net-strangeness distributions extracted from different strange particles show very different centrality and energy-dependence behavior. By comparing with the net-kaon fluctuations, we found that the strange baryons play an important role in the fluctuations of net strangeness. This study can provide useful baselines to study the QCD phase transition and search for the QCD critical point by using the fluctuations of net strangeness in heavy-ion collisions experiment. It can help us to understand noncritical physics contributions to the fluctuations of net strangeness.
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.
作者机构:
[Xiao, Kai; Liu, Feng; Wang, Fu-Qiang] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.;[Xiao, Kai; Liu, Feng; Wang, Fu-Qiang] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;[Xiao, Kai; Liu, Feng] South Cent Univ Nationalities, Coll Elect & Informat Engn, Wuhan 430074, Hubei, Peoples R China.;[Wang, Fu-Qiang] Purdue Univ, Dept Phys, W Lafayette, IN 47907 USA.;[Wang, Fu-Qiang] Huzhou Univ, Sch Sci, Huzhou 313000, Zhejiang, Peoples R China.
通讯机构:
[Xiao, Kai] C;[Xiao, Kai] S;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.;South Cent Univ Nationalities, Coll Elect & Informat Engn, Wuhan 430074, Hubei, Peoples R China.
关键词:
elliptic flow fluctuations;eccentricity;initial configuration;parton-parton interactions;hadronization and hadronic scatterings
摘要:
Sources of event-by-event elliptic flow fluctuations in relativistic heavy-ion collisions are investigated in a multiphase parton transport model (AMPT). Besides the well-known initial eccentricity fluctuations, several other sources of elliptic flow dynamical fluctuations are identified. One is fluctuations in initial parton configurations at a given eccentricity. Configuration fluctuations are found to be as important as eccentricity fluctuations in elliptic flow development. A second is quantum fluctuations in parton-parton interactions during system evolution. A third is fluctuations caused by hadronization and final-state hadronic scatterings. The magnitudes of these fluctuations are investigated relative to the eccentricity fluctuations and the average elliptic flow magnitude. The fluctuations from the latter two sources are found to be negative. The results may have important implications for the interpretation of elliptic flow data.
作者机构:
[Luo, Xiaofeng] 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:
[Luo, Xiaofeng] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.
摘要:
Fluctuations of conserved quantities are sensitive observables to probe the signature of QCD phase transition and critical point in heavy-ion collisions. With the UrQMD model, we have studied the centrality and energy dependence of various order cumulants and cumulant ratios (up to fourth order) of net-proton, net-charge, and net-kaon multiplicity distributions in Au+Au collisions at sNN=7.7, 11.5, 19.6, 27, 39, 62.4, 200 GeV. The model results show that the production mechanism of the particles and antiparticles has significant impact on the cumulants of net-particles multiplicity distributions and shows strong energy dependence. We also made comparisons between model calculations and experimental data measured in the first phase of the beam energy scan (BES) program by the STAR experiment at the BNL Relativistic Heavy Ion Collider. The comparisons indicate that the baryon conservation effect strongly suppresses the cumulants of net-proton distributions at low energies and the nonmonotonic energy dependence for the net-proton κσ2 at the most central Au+Au collisions measured by the STAR experiment cannot be described by the UrQMD model. Since there has been no physics of QCD phase transition and QCD critical point implemented in the UrQMD, the model results provide us baselines and qualitative estimates about the noncritical background contributions to the fluctuations observables in heavy-ion collisions.
摘要:
Momentum-space azimuthal harmonic event planes (EP) are constructed from final-state midrapidity particles binned in transverse momentum (pT) in sNN=200 GeV Au+Au collisions in a multiphase transport (AMPT) model. The EP correlations between pT bins, corrected by EP resolutions, are smaller than unity. This indicates that the EP's decorrelate over pT in AMPT, qualitatively consistent with data and hydrodynamic calculations. It is further found that the EP correlations approximately factorize into single pT-bin EP correlations to a common plane. This common plane appears to be the momentum-space EP integrated over all pT, not the configuration-space participant plane (PP).
摘要:
We trace the development of azimuthal anisotropy (nu(n), n = 2, 3) via parton-parton collision history in two transport models. The parton nu(n) is studied as a function of the number of collisions of each parton in Au + Au and d + Au collisions at root s(NN) = 200 GeV. It is found that the majority of nu(n) comes from the anisotropic escape probability of partons, with no fundamental difference at low and high transverse momenta. The contribution to nu(n) from hydrodynamic-type collective flow is found to be small. Only when the parton-parton cross-section is set unrealistically large does this contribution start to take over. Our findings challenge the current paradigm emerged from hydrodynamic comparisons to anisotropy data. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
作者机构:
[Zhou, You] Univ Copenhagen, Niels Bohr Inst, Blegdamsvej 17, DK-2100 Copenhagen, Denmark.;[Feng, Zhao; Xiao, Kai; Liu, Feng] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Feng, Zhao; Xiao, Kai; Liu, Feng] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Xiao, Kai] South Cent Univ Nationalities, Wuhan 430074, Peoples R China.;[Snellings, Raimond] Univ Utrecht, POB 80000, NL-3508 TA Utrecht, Netherlands.
通讯机构:
[Zhou, You] U;[Liu, Feng] C;Univ Copenhagen, Niels Bohr Inst, Blegdamsvej 17, DK-2100 Copenhagen, Denmark.;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:
With a multiphase transport (AMPT) model we investigate the relation between the magnitude, fluctuations, and correlations of the initial state spatial anisotropy ɛn and the final state anisotropic flow coefficients vn in Au+Au collisions at sNN=200 GeV. It is found that the relative eccentricity fluctuations in AMPT account for the observed elliptic flow fluctuations, both are in agreement with the elliptic flow fluctuation measurements from the STAR collaboration. In addition, the studies based on two- and multiparticle correlations and event-by-event distributions of the anisotropies suggest that the elliptic-power function is a promising candidate of the underlying probability density function of the event-by-event distributions of ɛn as well as vn. Furthermore, the correlations between different order symmetry planes and harmonics in the initial coordinate space and final state momentum space are presented. Nonzero values of these correlations have been observed. The comparison between our calculations and data will, in the future, shed new insight into the nature of the fluctuations of the quark-gluon plasma produced in heavy ion collisions.
作者机构:
[Peng, G. X.; Xu, J. F.] Univ Chinese Acad Sci, Sch Phys, Beijing 101408, Peoples R China.;[Peng, G. X.] Inst High Energy Phys, Theoret Phys Ctr Sci Facil, Beijing 100049, Peoples R China.;[Hou, De-Fu; Liu, F.] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Hou, De-Fu; Liu, F.] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Chen, Lie-Wen] Shanghai Jiao Tong Univ, Dept Phys & Astron, Shanghai 200240, Peoples R China.
通讯机构:
[Peng, G. X.] U;Univ Chinese Acad Sci, Sch Phys, 380 Huaibeizhen, Beijing 101408, Peoples R China.
摘要:
A quark model with running coupling and running strange quark mass, which is thermodynamically self-consistent at both high and lower densities, is presented and applied to study properties of strange quark matter and structure of compact stars. An additional term to the thermodynamic potential density is determined by meeting the fundamental differential equation of thermodynamics. It plays an important role in comparatively lower density and ignorable at extremely high density, acting as a chemical-potential dependent bag constant. In this thermodynamically enhanced perturbative QCD model, strange quark matter still has the possibility of being absolutely stable, while the pure quark star has a sharp surface with a maximum mass as large as about 2 times the solar mass and a maximum radius of about 11 kilometers.
作者机构:
[Zhang, Liang; Wang, Fuqiang; Liu, Feng] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Zhang, Liang; Wang, Fuqiang; Liu, Feng] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Wang, Fuqiang] Purdue Univ, Dept Phys & Astron, W Lafayette, IN 47907 USA.
通讯机构:
[Zhang, Liang] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.
摘要:
We investigate the survival rate of an initial momentum anisotropy (v2ini), not spatial anisotropy, to the final state in a multiphase transport (AMPT) model in Au+Au collisions at sNN=200 GeV. It is found that both the final-state parton and charged hadron v2 show a linear dependence versus v2ini{PP} with respect to the participant plane (PP). It is found that the slope of this linear dependence (referred to as the survival rate) increases with transverse momentum pT, reaching ∼100% at pT∼2.5 GeV/ c for both parton and charged hadron. The survival rate decreases with collision centrality and energy, indicating decreasing survival rate with increasing interactions. It is further found that a v2ini{Rnd} with respect to a random direction does not survive in v2{PP} but in the two-particle cumulant v2{2}. The dependence of v2{2} on v2ini{Rnd} is quadratic rather than linear.
作者机构:
Laboratory of Information Technologies, Joint Institute for Nuclear Research (JINR-LIT), Dubna, Russian Federation;GSI Helmholtzzentrum für Schwerionenforschung GmbH (GSI), Darmstadt, Germany;Institut für Kernphysik, Goethe Universität Frankfurt, Frankfurt, Germany;Department of Physics, Bose Institute, Kolkata, India;Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
摘要:
The paper shows the advances of research carroed out by the CBM (Compressed Barionic Matter) Collaboration at FAIR/GSI in Darmstadt.
作者机构:
[Yu, N.; Liu, F.] Cent China Normal Univ, MOE, Key Lab Quark & Lepton Phys, Wuhan 430079, Peoples R China.;[Yu, N.; Liu, F.] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Wu, K.] China Three Gorges Univ, Coll Sci, Yichang 443002, Peoples R China.
通讯机构:
[Yu, N.] C;Cent China Normal Univ, MOE, Key Lab Quark & Lepton Phys, Wuhan 430079, Peoples R China.
摘要:
Driven by the Beam Energy Scan (BES) program at the RHIC, researches and discussions on the QCD phase diagram have flourished recently. In order to provide a reference from microscopic transport models, we performed a systematic analysis, using a multiphase transport (AMPT) model for the particle yields and a statistical model (thermus) for the thermal fit, for Au + Au collisions at sNN=7.7–200 GeV. It is found that at a fixed collision centrality the chemical freeze-out parameter, temperature Tch, increases with collision energy and somehow saturates at certain values of Tch in collisions near sNN=10 GeV, indicating the limiting temperature in hadronic interactions; meanwhile the baryon chemical potential μB decrease with the collision energy. The saturation temperature is also found to be dependent on partonic interaction. At a given collision energy, it is found that both Tch and μB decrease towards more peripheral collisions in the grand canonical approach. The energy and centrality dependence of other chemical freeze-out parameters, strangeness chemical potential μS, strangeness undersaturation factor γS, and the volume of the fireball V are also presented in this paper. The chemical potential ratio μs/μB is also compared with lattice QCD calculation. The AMPT default model gives better descriptions on both the particle yields and the chemical freeze-out parameters than those from the AMPT string-melting model.
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:
This pilot study was to assess the high temperature and zero baryon density region of quantum chromodynamics (QCD) phase diagram with thermal photon emission, where the nature of QCD phase transition is ambiguous. Based on a (3+1)-D ideal hydrodynamical model to describe macroscopically the collision system, thermal photons emitted from Pb+Pb collisions at 2.76 TeV are investigated. The result reveals that photons from heavy ion collisions at high energy and centrality are possible to distinguish the structure of the hot dense matter, in QGP phase or hadronic phase, thus may provide an approach to explore the nature of this finite-temperature QCD transition (that is, first-order, second-order or analytic crossover).
作者机构:
[Xiao, Kai; Liu, Feng] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;[Xiao, Kai; Wang, Fuqiang; Liu, Feng] Cent China Normal Univ, Key Lab Quark & Lepton Phys, Minist Educ, Wuhan 430079, Hubei, Peoples R China.;[Wang, Fuqiang] Purdue Univ, Dept Phys, W Lafayette, IN 47907 USA.
通讯机构:
[Xiao, Kai] C;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.
摘要:
Within a multiphase transport model, we investigate decorrelation of event planes over pseudorapidity and its effect on azimuthal anisotropy measurements in relativistic heavy-ion collisions. The decorrelation increases with increasing η gap between particles used to reconstruct the event planes. The third harmonic event planes are found even anticorrelated between forward and backward rapidities, the source of which may root in the opposite orientation of the collision geometry triangularities. The decorrelation may call into question the anisotropic flow measurements with pseudorapidity gap designed to reduce nonflow contributions, hence the hydrodynamic properties of the quark-gluon plasma extracted from those measurements.
作者:
Agakishiev, G.*;Aggarwal, M. M.;Ahammed, Z.;Alakhverdyants, A. V.;Alekseev, I.;...
期刊:
PHYSICAL REVIEW C,2012年85(1) ISSN:2469-9985
通讯作者:
Agakishiev, G.
作者机构:
[Kechechyan, A.; Kizka, V.; Agakishiev, G.; Averichev, G. S.; Bunzarov, I.; Efimov, L. G.; Panebratsev, Y.; Alakhverdyants, A. V.; Shahaliev, E.; Rogachevskiy, O. V.; Fedorisin, J.; 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.; LeVine, M. J.; Ljubicic, T.; Xu, Z.; Ogawa, A.; Ruan, L.; Tang, A. H.; Fine, V.; Fisyak, Y.; Videbk, F.; Beavis, D. R.; Lauret, J.; Bland, L. C.; Longacre, R. S.; Webb, J. C.; Sorensen, P.; Christie, W.; Arkhipkin, D.; Debbe, R. R.; Lebedev, A.; Burton, T. P.; Dunlop, J. C.; Gordon, A.; Landgraf, J. M.; Yip, K.; Didenko, L.; Guryn, W.; Mitrovski, M. K.; 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; Mall, O. I.; Draper, J. E.; Cebra, D.; Brovko, S. G.; 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, G.] J;Joint Inst Nucl Res, Dubna 141980, Russia.
摘要:
This paper reports results for directed flow v(1) and elliptic flow v(2) of charged particles in Cu + Cu collisions at root s(NN) = 22.4 GeV at the Relativistic Heavy Ion Collider. The measurements are for the 0-60% most central collisions, using charged particles observed in the STAR detector. Our measurements extend to 22.4-GeV Cu + Cu collisions the prior observation that v1 is independent of the system size at 62.4 and 200 GeV and also extend the scaling of v(1) with eta/y(beam) to this system. The measured v(2)(p(T)) in Cu + Cu collisions is similar for root s(NN) throughout the range 22.4 to 200 GeV. We also report a comparison with results from transport model (ultrarelativistic quantum molecular dynamics and multiphase transport model) calculations. The model results do not agree quantitatively with the measured v(1)(eta), v(2)(p(T)), and v(2)(eta).
作者:
Agakishiev, G.*;Aggarwal, M. M.;Ahammed, Z.;Alakhverdyants, A. V.;Alekseev, I.;...
期刊:
PHYSICAL REVIEW C,2012年85(1) ISSN:2469-9985
通讯作者:
Agakishiev, G.
作者机构:
[Kechechyan, A.; Kizka, V.; Agakishiev, G.; Averichev, G. S.; Bunzarov, I.; Efimov, L. G.; Panebratsev, Y.; Alakhverdyants, A. V.; Shahaliev, E.; Rogachevskiy, O. V.; Fedorisin, J.; Zoulkarneeva, Y.; Tokarev, M.; Filip, P.; Lednicky, R.; Dedovich, T. G.; Vokal, S.] Joint Inst Nucl Res, Dubna 141980, Russia.;[Gliske, S.; Underwood, D. G.; Krueger, K.; 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.; Fisyak, Y.; Beavis, D. R.; Lauret, J.; Bland, L. C.; Longacre, R. S.; Webb, J. C.; Sorensen, P.; Christie, W.; Arkhipkin, D.; Debbe, R. R.; Lebedev, A.; Burton, T. P.; Dunlop, J. C.; Landgraf, J. M.; Yip, K.; Didenko, L.; Guryn, W.; Mitrovski, M. K.; 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; Mall, O. I.; Draper, J. E.; Cebra, D.; Brovko, S. G.; Sangaline, E.; Reed, R.; Romero, J. L.; Haag, B.] Univ Calif Davis, Davis, CA 95616 USA.
通讯机构:
[Agakishiev, G.] J;Joint Inst Nucl Res, Dubna 141980, Russia.
摘要:
Two-particle azimuthal (Delta phi) and pseudorapidity (Delta eta) correlations using a trigger particle with large transverse momentum (p(T)) in d+Au, Cu+Cu, and Au+Au collisions at root s(NN) = 62.4 GeV and 200 GeV from the STAR experiment at the Relativistic Heavy Ion Collider are presented. The near-side correlation is separated into a jet-like component, narrow in both Delta phi and Delta eta, and the ridge, narrow in Delta phi but broad in Delta eta. Both components are studied as a function of collision centrality, and the jet-like correlation is studied as a function of the trigger and associated p(T). The behavior of the jet-like component is remarkably consistent for different collision systems, suggesting it is produced by fragmentation. The width of the jet-like correlation is found to increase with the system size. The ridge, previously observed in Au+Au collisions at root s(NN) = 200 GeV, is also found in Cu+Cu collisions and in collisions at root s(NN) = 62.4 GeV, but is found to be substantially smaller at root s(NN) = 62.4 GeV than at root s(NN) = 200 GeV for the same average number of participants (< N-part >). Measurements of the ridge are compared to models.
期刊:
IEICE Transactions on Communications,2012年E95-B(9):2878-2883 ISSN:0916-8516
通讯作者:
Liu, Fan
作者机构:
[Li, Jun; Xu, Hongbo; Xia, Hongxing; Liu, Fan] Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
通讯机构:
[Liu, Fan] C;Cent China Normal Univ, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
关键词:
direct link;joint precoding;MIMO relay;non-regenerative
摘要:
This paper designs the closed-form precoding matrices for non-regenerative MIMO relay system with the direct link. A multiple power constrained non-convex optimization problem is formulated by using the minimum-mean-squared error (MMSE) criterion. We decompose the original problem into two sub-problems. The relay transceiver Wiener filter structure is first rigorously derived, then the source transmit and destination receive matrices are jointly designed by solving an equivalent dual problem. Through our proposed joint iterative algorithm, the closed-form solutions can be finally obtained. The effectiveness of our proposed scheme is validated by simulations with comparison to some of the existing schemes.