Hot QCD equation of state and quark-gluon plasma-- finite quark chemical potential

Gluon Condensate and Parton Propagation in a Quark-Gluon Plasma

A calculation of the thermal quark propagator is presented taking the gluon condensate above the critical temperature into account. The quark dispersion relation following from this propagator is derived.

Quark Propagation in a Quark-Gluon Plasma with Gluon Condensate

We present a calculation of the thermal quark propagator taking the gluon condensate above the critical temperature into account. The quark dispersion relation following from this propagator, describing two massive modes, is discussed.

No Pain, No Gain: Hard Probes of the Quark-Gluon Plasma Coming of Age

This lecture presents a concise review of the current status of hard QCD and electromagnetic processes as probes of the quark-gluon plasma.

Color randomization of fast gluon-gluon pairs in the quark-gluon plasma

We study the color randomization of two-gluon states produced after splitting of a primary fast gluon in the quark-gluon plasma. We find that for the LHC conditions the color randomization of the $gg$ pairs is rather slow. At jet energies $E=100$ and $500$ GeV, for typical jet path length in the plasma in central Pb+Pb collisions, the $SU(3)$-multiplet averaged color Casimir of the $gg$ pair differs considerably from its value $2N_c$ for a fully randomized $gg$ state. Our calculations of the energy dependence for generation of the nearly collinear decuplet $gg$ states, that can lead to the bar…

Erratum: Bremsstrahlung from an Equilibrating Quark-Gluon Plasma [Phys. Rev. C62, 014902 (2000)]

The implications of a numerical error in the photon production rate on the direct photon spectrum of a chemically non-equilibrated quark-gluon plasma are discussed.

Quest for the Quark-Gluon Plasma

Present status and future prospect of the quest for the quark-gluon plasma with untrarelativistic nuclear collisions are discussed.

Radiative quark $p_\perp$-broadening in a quark-gluon plasma at RHIC and LHC energies

We study the radiative correction to $p_\perp$-broadening of a fast quark in a quark-gluon plasma beyond the soft gluon approximation. We find that the radiative contribution to quark $\langle p_\perp^2\rangle$ for RHIC and LHC conditions is negative.

Broken symmetries and dilepton production from gluon fusion in a quark gluon plasma

The observational consequences of certain broken symmetries in a thermalised quark gluon plasma are elucidated. The signature under study is the spectrum of dileptons radiating from the plasma, through gluon fusion. Being a pure medium effect, this channel is non-vanishing only in plasmas with explicitly broken charge conjugation invariance. The emission rates are also sensitive to rotational invariance through the constraints imposed by Yang's theorem. This theorem is interpreted in the medium via the destructive interference between various multiple scattering diagrams obtained in the specta…

Gluon condensate, quark propagation, and dilepton production in the quark-gluon plasma

A calculation of the thermal quark propagator is presented taking the gluon condensate above the critical temperature into account. The quark dispersion relation and the dilepton production following from this propagator are derived.

Synchrotron contribution to photon emission from quark-gluon plasma

We study the influence of the magnetic field on the photon emission from the quark-gluon plasma created in $AA$ collisions. We find that even for very optimistic assumption on the magnitude of the magnetic field for noncentral $AA$ collisions the effect of magnetic field is very small.

Momentum Broadening in Weakly Coupled Quark-Gluon Plasma

We calculate the probability distribution P(k_\perp) for the momentum perpendicular to its original direction of motion that an energetic quark or gluon picks up as it propagates through weakly coupled quark-gluon plasma in thermal equilibrium.

Structure Functions and Pair Correlations of the Quark-Gluon Plasma

Recent experiments at RHIC and theoretical considerations indicate that the quark-gluon plasma, present in the fireball of relativistic heavy-ion collisions, might be in a liquid phase. The liquid state can be identified by characteristic correlation and structure functions. Here definitions of the structure functions and pair correlations of the quark-gluon plasma are presented as well as perturbative results. These definitions might be useful for verifying the quark-gluon-plasma liquid in QCD lattice calculations.

Dimuonium $(μ^+μ^-)$ Production in a Quark-Gluon Plasma

We study dimuonium $(μ^+μ^-)$ production in the quark-gluon plasma created in relativistic heavy ion collisions. The production is controlled by the process $q\bar q\rightarrow (μ^+μ^-)g$, and the dimuonium motion in the plasma is described by a transport equation. While the electrodynamics dominated dimuonium yield is not high enough, the transverse energy distribution carries the information of the plasma at RHIC and LHC energies.

Weakly and strongly coupled degrees of freedom in the quark-gluon plasma

In this talk, I reflect on the physical origin of the strongly coupled character of the quark-gluon plasma.

夸克-胶子等离子体中手性对辐射和能量损失的影响

Chiral effects on radiation and energy loss in quark-gluon plasma

本文研究了夸克-胶子等离子体中由sphaleron跃迁产生的涌现轴子对光子产生和能量损失的影响，回顾了手性切伦科夫效应及手性反常对轫致辐射的作用。

High-energy jet quenching in weakly-coupled quark-gluon plasmas

$\hat q$ is the average squared transverse momentum transfer per unit length to a high-energy particle traversing a QCD medium such as a quark-gluon plasma. We find the (UV-regulated) value of $\hat q$ to leading order in the weak coupling limit, $\alphas(T) \ll 1$. We then use this value to generalize previous analytic results on the gluon bremsstrahlung and pair production rates for massless high-energy particles in a weakly-coupled quark-gluon plasma, at next-to-leading logarithmic order.

Rotating quark-gluon plasma in relativistic heavy ion collisions

We study the rotational collective motion of the quark-gluon plasma in relativistic heavy ion collisions using the widely-adopted AMPT (A Multi-Phase Transport) model. The global angular momentum, the average vorticity carried by the quark-gluon plasma, and the locally defined vorticity fields are computed for Au+Au collisions, with detailed information of their time evolution, spatial distribution, as well as the dependence on beam energy and collision centrality.

Non-Perturbative Dilepton Production from a Quark-Gluon Plasma

The dilepton production rate from the quark-gluon plasma is calculated from the imaginary part of the photon self energy using a quark propagator that contains the gluon condensate. The low mass dilepton rate obtained in this way exhibits interesting structures (peaks and gaps), which might be observable at RHIC and LHC.

On the use of running $α_s$ in calculations of radiative energy loss of fast partons in a quark-gluon plasma

The incorporation of running $α_s$ for the gluon emission vertex in calculations of radiative parton energy loss in a quark-gluon plasma is discussed. It is argued that the virtuality scale for running $α_s$ for induced gluon emission is determined by the square of the transverse momentum of the emitted gluon rather than by the square of the invariant mass of the final two-parton state often used in the literature.

Screening Masses of Scalar and Pseudo-scalar Excitations in Quark-gluon Plasma

The quark-gluon plasma (QGP) excitations, corresponding to the scalar and pseudoscalar meson quantum numbers, for different temperatures are calculated. Analysis is performed in the Hard Thermal Loop (HTL) Approximation and leads to a better understanding of the excitations of QGP in the deconfined phase and is also of relevance for lattice studies.

夸克-胶子等离子体的物理和特征

Physics and Signatures of the Quark - Gluon Plasma

这是一个批判性的评论的各种观测值，已提出的信号从致密的强子物质的变化，夸克-胶子等离子体在高温或重子密度。讨论了相对论性重离子碰撞中夸克-胶子等离子体形成的现有模型，分析了各种模型的优点和不确定性。[The作者特别邀请有兴趣的读者在这篇评论发表之前就可能的不准确或遗漏提出评论。

Radiative Energy-Loss of Heavy Quarks in a Quark-Gluon Plasma

We estimate the radiative energy-loss of heavy quarks, produced from the initial fusion of partons, while propagating in a quark-gluon plasma which may be formed in the wake of relativistic heavy ion collisions. We find that the radiative energy-loss for heavy quarks is larger than the collisional energy-loss for all energies. We point out the consequences on possible signals of the quark-gluon plasma.

夸克-胶子等离子体形成的色单重态抑制

Color singlet suppression of quark-gluon plasma formation

在MIT袋模型下计算了过热强子物质中夸克-胶子等离子体液滴成核速率。色单态和（在较小程度上）固定动量的要求抑制成核率的许多数量级，使热成核的夸克-胶子等离子体液滴不太可能在超相对论重离子碰撞，如果过渡是一阶的，合理地描述了袋模型。

Electromagnetic response of quark-gluon plasma in heavy-ion collisions

We study the electromagnetic response of the quark-gluon plasma in AA-collisions at RHIC and LHC energies for a realistic space-time evolution of the plasma fireball. We demonstrate that for a realistic electric conductivity the electromagnetic response of the plasma is in a quantum regime when the induced electric current does not generate a classical electromagnetic field, and can only lead to a rare emission of single photons.

Gluon dissociation of $J/ψ$ in anisotropic {\em Quark-Gluon-Plasma}

We calculate the gluon dissociation cross-section in an anisotropic quark gluon plasma expected to be formed due relativistic nucleus-nucleus collisions. The initial rapid longitudinal expansion of the system leads to momentum space anisotropy due which the observables are affected in such a system. We show that the thermally weighted cross-section of gluon dissociation undergoes modification in anisotropic plasma leading to a decreased probability of $J/ψ$ suppression both for RHIC and LHC energies. The dependence of the cross section as well as the survival probability on the direction of pr…

Glueballs and statistical mechanics of the gluon plasma

We study a pure gluon plasma in the context of quasiparticle models, where the plasma is considered as an ideal gas of massive bosons. In order to reproduce SU(3) gauge field lattice data within such a framework, we review briefly the necessity to use a temperature-dependent gluon mass which accounts for color interactions between the gluons near $T_{\text{c}}$ and agrees with perturbative QCD at large temperatures. Consequently, we discuss the thermodynamics of systems with temperature-dependent Hamiltonians and clarify the situation about the possible solutions proposed in the literature to …

Hard probes of non-equilibrium quark-gluon plasma

Jets and photons could play an important role in finding the transport coefficients of the quark-gluon plasma. To this end we analyze their interaction with a non-equilibrium quark-gluon plasma. Using new field-theoretical tools we derive two-point correlators for the plasma which show how instabilities evolve in time. This allows us, for the first time, to derive finite rates of interaction with the medium. We furthermore show that coherent, long-wavelength instability fields in the Abelian limit do not modify the rate of photon emission or jet-medium interaction.

Viscous Quark-Gluon Plasma Model Through Fluid QCD Approach

A Lagrangian density for viscous quark-gluon plasma has been constructed within the fluid-like QCD framework. Gauge symmetry is preserved for all terms inside the Lagrangian, except for the viscous term. The transition mechanism from point particle field to fluid field, and vice versa, is discussed. The energy momentum tensor that is relevant for the gluonic plasma having the nature of fluid bulk of gluon sea is derived within the model. By imposing conservation law in the energy momentum tensor, shear viscosity appears as extractable from the equation.

Dilepton Production from Rho-Mesons in a Quark-Gluon Plasma

Assuming that rho-mesons exist in a quark-gluon plasma close to the QCD phase transition, we calculate the dilepton production rate from quark-antiquark annihilation via a rho-meson state using Vector Meson Dominance. The result is compared to the rates from direct quark-antiquark annihilation and from pion annihilation. Furthermore we discuss the suppression of low mass dileptons if the quarks assume an effective mass in the quark-gluon plasma.

Nucleation of Quark--Gluon Plasma Droplets

The energy densities achieved during central collisions of large nuclei at the AGS may be high enough to allow the formation of quark--gluon plasma. We propose that most collisions at AGS energies produce superheated hadronic matter, but in rare events a droplet of quark--gluon plasma is nucleated. We estimate the probability of this to occur based on homogeneous and inhomogeneous nucleation theory and discuss possible experimental signals.

Many-Body Physics: Collective fermionic excitations in quark-gluon plasmas and cold atom systems

In this talk I discuss collective excitations that carry fermion quantum numbers. Such excitations occur in the quark-gluon plasma and can also be produced in cold atom systems under special conditions.

Some Applications of Thermal Field Theory to Quark-Gluon Plasma

The lecture provides a brief introduction of thermal field theory within imaginary time formalism, the Hard Thermal Loop perturbation theory and some of its application to the physics of the quark-gluon plasma, possibly created in relativistic heavy ion collisions.

The refractive index in the viscous quark-gluon plasma

Under the framework of the viscous chromohydrodynamics, the gluon self-energy is derived for the quark-gluon plasma with shear viscosity. The viscous electric permittivity and magnetic permeability are evaluated from the gluon self-energy, through which the refraction index %in the %viscous quark-gluon plasma is investigated. The numerical analysis indicates that the refractive index becomes negative in some frequency range. The start point for that frequency range is around the electric permittivity pole, and the magnetic permeability pole determines the end point. As the increase of $η/s$, t…

夸克-胶子等离子体中的色手征切伦科夫辐射与能量损失

Color Chiral Cherenkov radiation and energy loss in quark-gluon plasma

本研究引入并探究色手征切伦科夫效应，推导了所有胶子极化的跃迁速率，计算了该效应对夸克-胶子等离子体中部分子能量损失的贡献。

Probes of the quark-gluon plasma and plasma instabilities

Penetrating probes in heavy-ion collisions, like jets and photons, are sensitive to the transport coefficients of the produced quark-gluon plasma, such as shear and bulk viscosity. Quantifying this sensitivity requires a detailed understanding of photon emission and jet-medium interaction in a non-equilibrium plasma. Up to now, such an understanding has been hindered by plasma instabilities which arise out of equilibrium and lead to spurious divergences when evaluating the rate of interaction of hard probes with the plasma. In this paper, we show that taking into account the time evolution of …

How big is the source that produces quark gluon plasma in heavy ion collisions?

We study, for the first time, the spatial extension of the "source" that produces quark gluon plasma (QGP) in ultra relativistic heavy ion collisions. The longitudinal dimension is studied as a function of time as the system evolves. The source size is found to exhibit a novel non-classical feature.

过冷夸克-胶子等离子体的类时冲击强子化

Time-Like Shock Hadronization of a Supercooled Quark-Gluon Plasma

研究了夸克-胶子等离子体不连续跃迁到强子物质态的能量动量守恒和重子数守恒定律。我们发现过冷夸克-胶子等离子体的类时激波强子化（当不连续超曲面的法向量是类时的时候）应该发生。我们考虑了这个过程的一些性质，它不同于标准的类空激波强子化。

夸克-胶子等离子体的寿命和高能光子强度干涉测量的混合相

Longevity of the quark-gluon plasma and the mixed phase from intensity interferometry of high energy photons

利用双光子强度干涉测量技术，通过测量外关联半径和侧关联半径的差异，精确测量了超相对论重离子碰撞中产生的夸克-胶子等离子体的寿命.在假设等离子体具有纵向的、boost不变的膨胀的条件下，我们得到了夸克-胶子等离子体相位关联的解析表达式。一个$3+1$尺寸膨胀的等离子体随着一阶相变强子是接下来考虑的，并导致一个源有两个特征寿命，一个为夸克-胶子等离子体相，和其他的较长寿命的混合相。这甚至可以帮助我们{ \em experimentally}确定相变的顺序。

Wakes in a Collisional Quark-Gluon Plasma

Wakes created by a parton moving through a static and infinitely extended quark-gluon plasma are considered. In contrast to former investigations collisions within the quark-gluon plasma are taken into account using a transport theoretical approach (Boltzmann equation) with a Bhatnagar-Gross-Krook collision term. Within this model it is shown that the wake structure changes significantly compared to the collisionless case.

夸克-胶子等离子体物理

Physics of the Quark-Gluon Plasma

能量远高于1 GeV/核子的中心核碰撞可以提供条件，在那里可以探测从高激发强子物质到夸克物质或夸克-胶子等离子体的跃迁。在这里，我回顾了我们目前对夸克-胶子等离子体的物理性质的理解，并回顾了关于解除禁闭跃迁的性质和信号的想法。我还详细介绍了最近的进展，在治疗的热化状态的形成部分子水平。

RHIC和LHC夸克-胶子等离子体的形成和演化

Formation and Evolution of Quark-Gluon Plasma at RHIC and LHC

在最低阶微扰QCD中考虑了在$τ=0.1\fm$上形成夸克-胶子等离子体的初始条件。研究了半硬夸克-胶子系统的化学组成、热化过程，特别是在小$x$处增强的新HERA部分子分布的意义。在RHIC和LHC上，$τ=0.1\fm$的等离子体都是强胶子主导的，并指出了在LHC上胶子快速热化的可能性。在计算中的Understanding，特别是阴影修正的部分子分布，进行了讨论。自由流动和理想的氢极限的胶子等离子体的演化与计算的minijet初始条件的证明，并获得LHC核碰撞的最终多重性的下限。

Hadron Formation From Quark-Gluon Plasma Using Lattice QCD At Finite Temperature

Recently we have reported the correct formulation of the lattice QCD method at the zero temperature to study the hadron formation from the quarks and gluons by incorporating the non-zero boundary surface term in QCD which arises due to the confinement of quarks and gluons inside the finite size hadron. In this paper we extend this to the finite temperature QCD and present the correct formulation of the lattice QCD method at the finite temperature to study the hadron formation from the quark-gluon plasma.

Momentum Broadening in Weakly Coupled Quark-Gluon Plasma (with a view to finding the quasiparticles within liquid quark-gluon plasma)

We calculate P(k_\perp), the probability distribution for an energetic parton that propagates for a distance L through a medium without radiating to pick up transverse momentum k_\perp, for a medium consisting of weakly coupled quark-gluon plasma. We use full or HTL self-energies in appropriate regimes, resumming each in order to find the leading large-L behavior. The jet quenching parameter \hat q is the second moment of P(k_\perp), and we compare our results to other determinations of this quantity in the literature, although we emphasize the importance of looking at P(k_\perp) in its entire…

Comment on `Charged Particle Ratio Fluctuation as a Signal for Quark-Gluon Plasma' and `Fluctuation Probes of Quark Deconfinement'

Charge fluctuations studied on event-by-event basis have been recently suggested to provide a signal of the equilibrium quark-gluon plasma produced in heavy-ion collisions at high energies. It is argued that the fluctuations generated at the early collision stage when the energy is released can fake the signal.

Signals of the quark-gluon plasma in nucleus-nucleus collisions

This talk is a brief overview of the present status of our understanding of nucleus-nucleus collisions at high energy and the search for signals of the quark-gluon plasma.

High energy photons from passage of jets through quark gluon plasma

We calculate the production of high energy photons from Compton scattering and annihilation of a quark jet passing through a quark gluon plasma produced in a relativistic heavy ion collision. The contributions are large and reflect the momentum distribution of the jets and the initial conditions of the plasma.

Quarkonium in a weakly-coupled quark-gluon plasma

We report about a recent calculation of the heavy quarkonium mass and decay width in a quark-gluon plasma, whose temperature T and screening mass m_D satisfy the hierarchy m alpha_s >> pi T >> m alpha_s^2 >> m_D, m being the heavy-quark mass, up to order m alpha_s^5. The calculation may be relevant to understand the behavior of the Y(1S) in a quark-gluon plasma at present-day colliders.

Chromodynamic Fluctuations in Quark-Gluon Plasma

Fluctuations of chromodynamic fields in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average colorless, stationary and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long-time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum which is provided by the fluctuation-dissipation relation. Fluctuations in the unstable plasma, where the memory of initial fluctuations is not lost, are also discussed.

Dilepton production and elliptic flow from an anisotropic quark-gluon plasma

We calculate the yield and elliptic flow of mid-rapidity dileptons emitted from the quark-gluon plasma generated in Pb-Pb collisions at LHC. We use relativistic anisotropic hydrodynamics for the 3+1 dimensional evolution of the quark-gluon plasma and convolve this with the momentum-anisotropic local rest frame production rate for dileptons. The effects of momentum anisotropy of the quark distribution functions, viscosity to entropy density ratio, centrality of the collisions, and initial momentum anisotropy on the results are investigated and discussed.

Effect of magnetic field on the photon radiation from quark-gluon plasma in heavy ion collisions

We develop a formalism for the photon emission from the quark-gluon plasma with an external electromagnetic field. We then use it to investigate the effect of magnetic field on the photon emission from the quark-gluon plasma created in $AA$ collisions. We find that even for very optimistic assumption on the magnitude of the magnetic field generated in $AA$ collisions its effect on the photon emission rate is practically negligible. For this reason the magnetic field cannot generate a significant azimuthal asymmetry in the photon spectrum.

Quark Dispersion Relation and Dilepton Production in the Quark-Gluon Plasma

Under very general assumptions we show that the quark dispersion relation in the quark-gluon plasma is given by two collective branches, of which one has a minimum at a non-vanishing momentum. This general feature of the quark dispersion relation leads to structures (van Hove singularities, gaps) in the low mass dilepton production rate, which might provide a unique signature for the quark-gluon plasma formation in relativistic heavy ion collisions.

Measuring Quark-Gluon-Plasma Thermalization Time with Dileptons

We calculate the medium dilepton yield from a quark-gluon plasma which has a time-dependent local momentum-space anisotropy. A phenomenological model for the hard momentum scale, p_hard(tau), and plasma anisotropy parameter, xi(tau), is constructed which interpolates between free streaming behavior at early times (tau << tau_iso) and ideal hydrodynamic behavior at late times (tau >> tau_iso). We show that high-energy dilepton production is sensitive to the assumed plasma isotropization time, tau_iso, and can therefore be used to experimentally determine the time of onset for hydrodynamic expan…

Signals in Single-Event Pion Interferometry for Granular Sources of Quark-Gluon Plasma Droplets

We investigate two-pion Bose-Einstein correlations of quark-gluon plasma droplet sources in single-event measurements. We find that the distribution of the fluctuation between correlation functions of the single- and mixed-events provide useful signals to detect the granular structure of the source.

强子化夸克-胶子等离子体中双轻子的快度分布

Rapidity Distributions of Dileptons from a Hadronizing Quark-Gluon Plasma

双轻子的产生可以作为夸克-胶子等离子体的探针。我们计算了由演化的夸克-胶子等离子体产生的热双轻子的快度分布，假设一个纵向标度展开，初始条件由强子快度密度局部确定。这些分布进行了比较，与Drell-Yan生产和半轻子魅力衰变在不变质量$M = 2$，4，和6 GeV。