共查询到20条相似文献,搜索用时 500 毫秒
1.
利用QGP中存在德拜屏蔽现象以及高温极限下QGP中夸克的分布函数和色电势,得到QGP中夸克静色电波的辐射功率. 讨论了夸克静色电波的辐射功率与德拜长度λD的关系,有助于利用辐射功率研究德拜屏蔽位势. 相似文献
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The thermodynamic properties of the quark-gluon plasma (QGP), as well as its phase diagram, are calculated as a function of baryon density (chemical potential) and temperature. The QGP is assumed to be composed of the light quarks only, i.e., the up and down quarks, which interact weakly, and the gluons which are treated as they are free. The interaction between quarks is considered in the framework of the one gluon exchange model which is obtained from the Fermi liquid picture. The bag model is used, with fixed bag pressure (B)for the nonperturbative part, and the quantum chromodynamics (QCD) coupling is assumed to be constant, i.e., with no dependence on the temperature or the baryon density. The effect of weakly interacting quarks on the QGP phase diagram are shown and discussed. It is demonstrated that the one-gluon exchange interaction for the massless quarks has considerable effect on the QGP phase diagram and it causes the system to reach to the confined phase at the smaller baryon densities and temperatures. The pressure of excluded volume hadron gas model is also used to find the transition phase diagram. Our results depend on the values of bag pressure and the QCD coupling constant. The latter does not have a dramatic effect on our calculations. Finally, we compare our results with the thermodynamic properties of strange quark matter and the lattice QCD prediction for the QGP transition critical temperature. 相似文献
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Heavy quarks play an important role in probing the properties of strongly interacting quark-gluon plasma(QGP)created in ultra-relativistic heavy-ion collisions.We study the interactions of single heavy(charm)quarks and correlated charm and anticharm(ccˉ)quark pairs with the medium constituents of QGP by performing fireball+Langevin simulations of the pertinent Brownian motion with elastic collisions.Besides studying the traditional observables,the nuclear modification factor and the elliptic flow of single heavy quarks in QGP for different thermal relaxation rates,we also study the broadening of the azimuthal correlations of charm and anticharm quark pairs in the QGP medium for different relaxation rates and transverse momenta classes.We quantified the smearing of ccˉpair azimuthal correlations with an increasing thermal relaxation rate:while the(nearly)back-to-back correlations among ccˉpairs are almost completely washed out at low transverse momentum(pT),these correlations at high pT largely survive the pair diffusion.This provides a novel observable for diagnosing the properties of QGP. 相似文献
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Nielsen and Olesen showed that perturbative vacuum with uniform chromomagnetic field in one space and one color direction
is unstable. This instability is called Nielsen-Olesen instability (NOI), and leads to formation of a ‘spaghetti of flux tubes’
as a model for non-perturbative vacuum and confinement. We re-examine this instability in presence of color sources, quarks
and gluons, at a finite temperature and find that at sufficiently high temperature NOI is stabilized due to an ‘effective
mass’ of gluons arising through plasma effects. This explains how a QGP with no confinement effects may exist at high temperature.
As the temperature is lowered, NOI reappears at a valueT=T
c, which is very close to confinement-deconfinement transition from hadrons to QGP.. 相似文献
6.
First-Principles Calculations of Elastic Properties of LaNi4.75Sn0.25 Alloys under Pressure
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The equilibrium lattice constants, bulk modulus, shear modulus, elastic constants and Debye temperature of LaNi4.75 Sn0.25 under pressure are calculated using the full-potential linearized augmented plane wave (FP-LAPW) method as well as the quasi-harmonic Debye model. The results at zero pressure are in excellent agreement with the experimental data. The Sn atom is found to occupy the equivalent 3g site (0.5a, 0.75b, 0.5c) in the quadruple cell. The Debye temperature of LaNi4.75Sn0.25 is lower than that of LaNi5. The dependences of bulk modulus on finite temperature and on finite pressure are also investigated. The results show that the bulk modulus B increases monotonously as pressure increases. 相似文献
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夸克胶子等离子体中的次带头阶得拜屏蔽质量 总被引:1,自引:0,他引:1
采用实时有限温度下的QCD,考虑到胶子的衰减率计算了QGP中次领头阶得拜屏蔽质量的贡献,克服了通常计算中的红外发散的困难,且不必引入非微扰的磁屏蔽质量作红外截断.指出了所得结果的正定性和规范无关性并与格点模拟的结果进行了比较. 相似文献
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双轻子是研究夸克物质的形成和性质的重要探针.本文基于化学平衡化的黏滞性夸克胶子等离子体演化模型,计算了相对论重离子碰撞能量下金-金对心碰撞形成的夸克胶子等离子体中的双轻子产额.在黏滞性计算中加入了胶子非弹性散射过程对黏滞系数的贡献.相较仅考虑夸克和胶子弹性散射的情况,双轻子的产额有较明显的降低.这表明在黏滞系数中加入胶子非弹性散射的贡献使得系统的演化过程加快,演化时间变短. 相似文献
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We discuss enhancement of multiplicities of hadrons at high transverse momentum due to multiple reflections of quarks from
collapsing Z(3) interfaces in the QGP produced in relativistic heavy-ion collisions. By modeling the dependence of effective
mass of the quarks on the Polyakov loop order parameter, we evaluate the reflection coefficient of quarks from collapsing
Z(3) interfaces. We use the effective potential proposed by Pisarski for the Polyakov loop to determine the profile of the
Z(3) interfaces and calculate the reflection probability for quarks. We discuss the formation of a network of these Z(3) walls
in relativistic heavy-ion collisions, in the QGP phase. We do a numerical simulation to calculate the modifications in the
thermal transverse momentum spectra of the quarks/anti-quarks that results from a collapsing wall. We then use the recombination
model to calculate the transverse momentum spectrum of final hadrons. Our results show enhancement of high P
T
hadrons, with the enhancement being stronger for heavier quarks. Further, we find that due to larger reflection coefficient
for heavier quarks, the density of strange and charm quarks/anti-quarks increases inside the collapsing walls. This implies
enhancement in the multiplicities of multi-strange and multi-charmed hadrons. 相似文献
10.
The next-to-leading order Debye screening mass in QGP is calculated by taking into account the damping rate of gluons in the formalism of real time finite temperature QCD, and the infrared singularity of the naive calculation is cured without adding a nonperturbative magnetic screening mass as a cutoff. In addition, the result is shown to be postive and gauge-independent, and is compared with the results from lattice simulations. 相似文献
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The next-to-leading order Debye screening mass in QGP is calculated by taking into account the damping rate of gluons in the formalism of real time finite temperature QCD, and the infrared singularity of the naive calculation is cured without adding a nonperturbative magnetic screening mass as a cutoff. In addition, the result is shown to be postive and gauge-independent, and is compared with the results from lattice simulations. 相似文献
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YANG Xin-E 《中国物理C(英文版)》1985,9(5):537-541
We propose a composite model of leptons and quarks containing two constituent fermions of spin 1/2 and a constituent scalar. The constituent fermions are massless and color singlets. Leptons, quarks and weak vector bosons are composites confined by SU(3)H local gauge interaction, where leptons are made of three constituent fermions and quarks are two-body composites of a scalar and a fermion. The number of the constituent particles is less in our model. There are less exotic leptons and quarks. Quark-lepton parallelism holds. Weak interactions appear only at the composite level as residual short-range interactions among hypercolor singlets. The violation of parity occurs by the mechanism of dynamical symmetry breaking. 相似文献
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The non-perturbative effects for the Quark-Gluon Plasma (QGP) equation of state (EoS) are considered. The modifications of the bag model EoS are constructed to satisfy the main qualitative features observed for the QGP EoS in the lattice QCD calculations. A quantitative comparison with the lattice results is done for the SU(3) gluon plasma and for the QGP with dynamical quarks. Our analysis advocates a negative value of the bag constant B. 相似文献
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从动力论方程出发,考虑QGP中平均场效应,采用弛豫时问近似,给出了关于QGP输运系数的一种分析方法,推导出QGP中夸克输运系数解析式,讨论了QGP粘滞效应与导热效应. 相似文献
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Production and space-time evolution of heavy quarks in central and non-central heavy-ion collisions at RHIC and LHC are studied with the partonic transport model Boltzmann Approach of MultiParton Scatterings (BAMPS). In addition to the initially created heavy quarks in hard parton scatterings during nucleon-nucleon collisions, secondary heavy quark production in the quark-gluon plasma is investigated and the sensitivity on various parameters is estimated. In BAMPS heavy quarks scatter with particles of the medium via elastic collisions, whose cross section is calculated with the running coupling and a more precise implementation of Debye screening. In this framework, we compute the elliptic flow and nuclear modification factor of heavy quarks and compare it to the experimental data. 相似文献
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M. J. Leitch 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):868-874
At the Relativistic Heavy-Ion Collider (RHIC) collisions of heavy ions at nucleon-nucleon energies of 200GeV appear to have
created a new form of matter thought to be a deconfined state of the partons that ordinarily are bound in nucleons. We discuss
the evidence that a thermalized partonic medium, usually called a Quark Gluon Plasma (QGP), has been produced. Then, we discuss
the effect of this high-density medium on the production of jets and their pair correlations. Next, we look at direct photons
as a clean electro-magnetic probe to constrain the initial hard scatterings. Finally, we review the developing picture for
the effect of this medium on the production of open heavy quarks and on the screening by the QGP of heavy-quark bound states. 相似文献
19.
Screening of a moving infinite color sheet source is examined in a quark plasma at finite temperature. The classical chromohydrodynamic
equations for quarks are integrated, to obtain profiles for quark current density, which in turn are used to solve the SU(2)
Yang-Mills equations numerically. This provides a classical but non-perturbative treatment for the screening of a moving source
in quark plasma.
The results show two interesting features. We observe that if the test source is at rest the screening does not depend on
the color dynamics and the behavior is very similar to that in Coulomb plasma. When the test source is moving with non-relativistic
velocity the non-abelian features manifest themselves by weakening the screening and also by exhibiting an oscillatory profile
with distance. 相似文献
20.
The nucleation rate of quark-gluon plasma (QGP) droplet is computed at finite quark chemical potential. In the course of computing the nucleation rate, the finite size effects of the QGP droplet are taken into account. We consider the phenomenological flow parameter of quarks and gluons, which is dependent on quark chemical potential and we calculate the nucleation rate of the QGP droplet with this parameter. While calculating the nucleation rate, we find that for low values of quark phenomenological parameter ?? q , nucleation rate is negligible and when ?? q increases, nucleation rate increases significantly. 相似文献