摘要：
We present a self-consistent quasiparticle model to investigate the thermal properties of quark-gluon plasma above the critical temperature. All effects of the interactions among the partons are contained in the thermal mass of partons, so the system may be treated as an ideal gas of the massive quarks and gluons. From the statistical mechanics, we can calculate the thermodynamical quantities without any inconsistency, and then obtain a good fit to the lattice QCD data. The results show that the main degree of freedom is from quark-antiquark pairs, even at the high temperature. Finally, the quark number fluctuation is also analyzed. (c) 2009 Elsevier B.V. All rights reserved.
作者机构：
[Yang, C. B.; Hwa, Rudolph C.] Univ Oregon, Inst Theoret Sci, Eugene, OR 97403 USA.;[Yang, C. B.; Hwa, Rudolph C.] Univ Oregon, Dept Phys, Eugene, OR 97403 USA.;[Yang, C. B.] Huazhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Hwa, Rudolph C.] U;Univ Oregon, Inst Theoret Sci, Eugene, OR 97403 USA.
摘要：
The correlation between the trigger and associated particles in jets produced on near and away sides of high- pT triggers in heavy-ion collisions is studied. Hadronization of jets on both sides is treated by thermal-shower and shower-shower recombinations. The energy loss of semihard and hard partons traversing the nuclear medium is parametrized in a way that renders a good fit of the single-particle inclusive distributions at all centralities. The associated hadron distribution in the near-side jet can be determined showing weak dependence on system size because of trigger bias. The inverse slope increases with trigger momentum in agreement with data. The distribution of associated particles in the away-side jet is also studied with careful attention given to antitrigger bias that is due to the longer path length that the away-side jet recoiling against the trigger jet must propagate in the medium to reach the opposite side. Centrality dependence is taken into account after determining a realistic probability distribution of the dynamical path length of the parton trajectory within each class of centrality. For symmetric dijets with pTtrig=pTassoc(away), it is shown that the per-trigger yield is dominated by tangential jets. For unequal pTtrig, pTassoc(near) and pTassoc(away), the yields are calculated for various centralities, showing an intricate relationship among them. The near-side yield agrees with data both in centrality dependence and in pTassoc(near) distribution. The average parton momentum for the recoil jet is shown to be always larger than that of the trigger jet for fixed pTtrig and centrality and for any measurable pTassoc(away). With the comprehensive treatment of dijet production described here, it is possible to answer many questions regarding the behavior of partons in the medium under conditions that can be specified on measurable hadron momenta.
摘要：
With the experimental data from STAR on the multiplicity dependence of the transverse momentum spectra of charged particles in pp collisions at root(NN)-N-S = 200 GeV, we investigate the scaling property of the spectra in those collisions. Using the scaling functions of pion and proton obtained in studying spectra in Au + Au and d + Au collisions, we describe the charged particle PT spectra in pp collisions as a superposition of those front pion and proton. Species contents are obtained and p/pi ratio is given as a function Of PT for events with some given charged multiplicities. (c) 2008 Elsevier B.V. All rights reserved.
作者机构：
[Chiu, Charles B.] Univ Texas Austin, Ctr Particle Phys, Austin, TX 78712 USA.;[Chiu, Charles B.] Univ Texas Austin, Dept Phys, Austin, TX 78712 USA.;[Yang, C. B.; Hwa, Rudolph C.] Univ Oregon, Dept Phys, Eugene, OR 97403 USA.;[Yang, C. B.; Hwa, Rudolph C.] Univ Oregon, Inst Theoret Sci, Eugene, OR 97403 USA.;[Yang, C. B.] Hua Zhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Chiu, Charles B.] U;Univ Texas Austin, Ctr Particle Phys, Austin, TX 78712 USA.
摘要：
Azimuthal anisotropy is studied by taking into account the ridges created by semihard scattering, which is sensitive to the initial spatial configuration in noncentral heavy-ion collisions. No rapid thermalization is required. Although hydrodynamics is not used in this study, the validity of hydrodynamical expansion is not excluded at later time after equilibration is achieved. Phenomenological properties of the bulk and ridge behaviors are used as inputs to determine the elliptic flow of pion and proton at low pT. At intermediate pT the recombination of shower partons with thermal partons becomes more important. The ϕ dependence arises from the variation of the in-medium path length of the hard parton that generates the shower. The pT dependence of v2 is therefore very different at intermediate pT compared to that at low pT. Quark number scaling of v2 is shown to be only approximately valid at low pT, but is broken at intermediate pT, even though recombination is the mechanism of hadronization in all pT regions considered.
作者机构：
[Yang, C. B.; Zheng, H.; Zhu, L. L.] Huazhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Yang, C. B.] H;Huazhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
关键词：
scaling behavior;transverse energy;Au plus Au collisions
摘要：
With the experimental data from STAR on the centrality dependence of transverse momentum PT spectra of pions and protons in Au + An collisions at root s(NN) = 200 GeV, we investigate the scaling properties of transverse energy E-T distributions at different centralities. In the framework of cluster formation and decay mechanism for particle production, the universal transverse energy distributions for pion and proton can be described separately but not simultaneously. (C) 2008 Elsevier B.V. All rights reserved.
作者机构：
[Yang, C.B.] Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430079, China;[Hwa, R.C.] Institute of Theoretical Science, University of Oregon, Eugene, OR-97403, United States
期刊：
JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS,2008年35(5):055003- ISSN：0954-3899
通讯作者：
Zheng, H.
作者机构：
[Yang, C. B.; Zheng, H.] Hua Zhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Zheng, H.] H;Hua Zhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
摘要：
Uncertainties of five shower parton distributions in jets at fixed Q2 = 100 GeV2 are investigated from three sets of fragmentation functions in the framework of a quark recombination model.
作者机构：
[Yang, C. B.; Nie, W. X.; Zeng, Y.; Zhang, W. C.; Zhu, L. L.] Hua Zhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Zhang, W. C.] H;Hua Zhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
摘要：
With the experimental data from STAR and PHENIX on the centrality dependence of the pT spectra of protons and antiprotons produced at midrapidity in Au+Au collisions at 200 GeV, we show that for protons and antiprotons there exists a scaling distribution independent of the colliding centrality. The scaling functions can also describe data from BRAHMS for both proton and antiproton spectra at y=2.2 and 3.2. The scaling behaviors are shown to be incompatible with the usual string fragmentation scenario for particle production.
作者机构：
[Yang, C. B.; Zhu, L. L.] Hua Zhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Zhu, L. L.] H;Hua Zhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
摘要：
With the experimental data from the STAR, PHENIX, and BRAHMS programs on the centrality and rapidity dependence of the pT spectrum in Au+Au and d+Au collisions, we show that a scaling distribution exists that is independent of the colliding system, centrality, and rapidity. The parameter for the average transverse momentum 〈pT〉 increases from peripheral to central d+Au collisions. This increase accounts for the enhancement of particle production in those collisions. A nonextensive entropy is used to derive the scaling function.
作者机构：
[C. B. Yang] Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430079, People's Republic of China;[C. B. Yang; Rudolph C. Hwa] Institute of Theoretical Science and Department of Physics, University of Oregon, Eugene, Oregon 97403-5203, USA
摘要：
The recombination model is applied to the production of K , ϕ , Λ , and Ω at all p T in central Au+Au collisions. The thermal-shower component of the recombination is found to be important for K and Λ, but only in a minor way for ϕ and Ω in the intermediate to high p T region. The normalization and inverse slope of the thermal partons in the strange sector are determined by fitting the low- p T data. At higher p T the data of K , Λ , ϕ , and Ω in the log scale are all well reproduced in our study that extends the thermal contribution and includes the shower contribution. The calculated result on the Λ / K ratio rises to a maximum of around 2 at p T ≈ 4 GeV/ c , arching over the data in linear scale. The production of ϕ and Ω are shown to arise mainly from the recombination of thermal partons, thus exhibiting exponential p T dependences in agreement with the data. Their ratio, R Ω / ϕ , rises linearly to p T ≈ 4 GeV/ c and develops a maximum at p T ≈ 5 . 5 GeV/ c . It is argued that the p T spectra of ϕ and Ω reveal directly the partonic nature of the thermal source that characterizes quark-gluon plasma. Comments are made on the Ω puzzle due to the simultaneous observation of both the exponential behavior of the Ω spectrum in p T and the existence of low- p T particles associated with Ω as trigger.
作者机构：
[Yang, C. B.; Yang, CB] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Yang, CB] Univ Oregon
通讯机构：
[Yang, C. B.] C;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
会议名称：
19th International Conference on Ultra-Relativistic Necleus-Nucleus Collisions
会议时间：
NOV 14-20, 2006
会议地点：
Shanghai, PEOPLES R CHINA
会议主办单位：
Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.^Univ Oregon, Eugene, OR 97403 USA.
摘要：
The recombination model is applied to the production of K, Lambda, phi, and Omega at all p(T) in central Au+Au collisions. The thermal-shower component of the recombination is found to be important for K and Lambda in the intermediate p(T) region. For phi and Omega, the pure thermal recombination dominates up to 8 GeV/c. The contribution from shower strange quarks to multi-strange particle spectra can be seen from the Omega/Phi ratio.
