The effects of the non-extensive statistics on the nonlinear propagation of perturbations have been studied within the scope of relativistic second order dissipative hydrodynamics with the non-extensive equation of state. We have shown that the equations, describing the propagation of nonlinear waves under such situation are KdV-type (Korteweg-De Vries). Apart from their preserved solitonic behaviour the dissipative nature of these waves are also observed. The waves with larger amplitude and width dissipate less and propagate faster and these waves deplete more for both smaller values of Tsallis parameter ($q$) and temperature ($T$) of the medium. For vanishingly small transport coefficients the nonlinear waves show breaking nature. These findings suggest that the nature of the propagation of the nonlinear waves may serve as a good probe to differentiate between the extensive and non-extensive thermodynamic nature of a fluid, such as the quark-gluon plasma, produced in relativistic nuclear collisions.
We calculate the viscous pressure tensor of the quark-gluon plasma in strong magnetic field. It is azimuthally anisotropic and is characterized by five shear viscosity coefficients, four of which vanish when the field strength eB is much larger than the plasma temperature squared. We argue, that the azimuthally anisotropic viscous pressure tensor generates the transverse flow with asymmetry as large as 1/3, even not taking into account the collision geometry. We conclude, that the magnitude of the shear viscosity extracted from the experimental data ignoring the magnetic field must be underest…
We use quasiparticle anisotropic hydrodynamics to study the non-conformal and non-extensive dynamics of a system undergoing boost-invariant Bjorken expansion. To introduce nonextensivity, we use an underlying Tsallis distribution with a time-dependent nonextensivity parameter $q$. By taking moments of the quasiparticle Boltzmann equation in the relaxation-time approximation, we obtain dynamical equations which allow us to determine the time evolution of all microscopic parameters including $q$. We compare numerical solutions for bulk observables obtained using the nonextensive evolution with r…
The drag and diffusion coefficients are studied within the framework of Fokker-Planck dynamics for the case of a charm quark propagating in an expanding quark-gluon plasma. The space-time evolution of the nuclear matter created in the relativistic heavy-ion collision is modelled using MUSIC, a 3+1 D relativistic viscous hydrodynamic approach. The effect of viscous corrections to the heavy quark transport coefficients is explored by considering scattering processes with thermal quarks and gluons in the medium. It is observed that the momentum diffusion of the heavy quarks is sensitive to the sh…
We study the properties of quarkonia inside a bulk-viscous quark gluon plasma. The non-equilibrium nature of the medium is encoded in the deformed distribution functions of thermal quarks and gluons, with which we compute the dielectric permittivity within the hard thermal loop approximation at one-loop. The modified dielectric permittivity is used to calculate the in-medium heavy quark potential, and using the potential we compute spectral functions, which reflect the physical properties of heavy quarkonia. We discuss how the bulk viscous effect influences quantities such as binding energies …
We study the properties of heavy quarkonia in a quark-gluon plasma in the presence of bulk viscous effects. Within the hard thermal loop approximation at one-loop, the dielectric permittivity of quark-gluon plasma is computed, where the bulk viscous effect enters through the deformation of the distribution functions of thermal quarks and gluons. Based on the modified dielectric permittivity, we compute the in-medium heavy quark potential, that includes non-pertubative string-like terms as well as the perturbative Coulombic term. We discuss how the bulk viscous effect modifies the real and imag…
The bottom quark transport coefficients, i.e., drag and diffusion coefficients, have been studied for the collisional and soft gluon radiative processes within the viscous QCD medium. The thermal medium effects are incorporated using the effective fugacity quasiparticle model (EQPM). Both the shear and bulk viscous effects at leading order are embedded through the near-equilibrium distribution functions of the quark-gluon plasma (QGP) constituent quasiparticles. The transport coefficients' dependence on the bottom quark's initial momentum and QGP temperature has been investigated. The relative…
The non-equilibrium properties of quark-gluon plasma (QGP) have been a topic of intensive research. In this contribution, we explore the nature of heavy quarkonia immersed in a QGP with bulk viscosity. We incorporate the bulk viscous effect through the deformation of the distribution functions of thermal quarks and gluons, with which the color dielectric permittivity can be computed. We use the color dielectric permittivity to compute the heavy quark potential inside a bulk viscous plasma and solve the Schrödinger equation using the potential to obtain the physical properties such as binding e…
We study the response function which describes the evolution of energy density induced by an initial disturbance for a Bjorken-expanding quark-gluon plasma (QGP). We compare the results from solving linearized Boltzmann equation under the relaxation time approximation with those from viscous hydrodynamics. While in long time limit the response becomes hydrodynamics, the non-hydrodynamic response is important at intermediate times when excitations of wavelength larger than the inverse of the relaxation time $1/τ_{R}$ are not fully damped. Therefore observables sensitive to the jet-induced mediu…
Relativistic hydrodynamics represents a powerful tool to investigate the time evolution of the strongly interacting quark gluon plasma created in ultrarelativistic heavy ion collisions. The equations are solved often numerically, and numerous analytic solutions also exist. However, the inclusion of viscous effects in exact, analytic solutions has received less attention. Here we utilize Hubble flow to investigate the role of bulk viscosity, and present different classes of exact, analytic solutions valid also in the presence of dissipative effects.
The second-order hydrodynamic equations for evolution of shear and bulk viscous pressure have been derived within the framework of covariant kinetic theory based on the effective fugacity quasiparticle model. The temperature-dependent fugacity parameter in the equilibrium distribution function leads to a mean field term in the Boltzmann equation which affects the interactions in the hot QCD matter. The viscous corrections to distribution function, up to second-order in gradient expansion, have been obtained by employing a Chapman-Enskog like iterative solution of the effective Boltzmann equati…
Harish-Chandra Research Institute, A CI of Homi Bhabha National Institute（哈里什-昌德拉研究所，霍米·巴哈国家学院下属机构）；Instituto de Fisica Gleb Wataghin, University of Campinas（坎皮纳斯大学格列布·瓦塔金物理研究所）；Department of Physics and Astronomy, University of Alabama（阿拉巴马大学物理与天文学系）；Institute for Theoretical Physics and Astrophysics, Julius-Maximilians Universität Würzburg（维尔茨堡朱利叶斯-马克西米利安大学理论与天体物理研究所）；Shanghai Institute for Mathematics and Interdisciplinary Sciences (SIMIS)（上海数学与交叉学科研究院）
The effects of longitudinal bulk viscous pressure on the heavy quark dynamics have been estimated in a strongly magnetized quark-gluon plasma within the Fokker-Planck approach. The bulk viscous modification to the momentum distribution of bulk degrees of freedom has been obtained in the presence of a magnetic field while incorporating the realistic equation of state of the hot magnetized QCD medium. As the magnetic field breaks the isotropy of the medium, the analysis is done along the directions longitudinal and transverse to the field. The longitudinal bulk viscous contribution is seen to ha…
Hadron spectra and elliptic flow for 200 A GeV Au+Au collisions from viscous hydrodynamics coupled to a Boltzmann cascade
结果表明，最近开发的混合代码VISHNU，耦合的相对论粘性流体动力学描述的夸克-胶子等离子体（QGP）与微观玻尔兹曼级联的强子再散射后期阶段，产生一个很好的描述带电和识别的强子谱和椭圆流测量在200 A GeV的Au+Au碰撞在相对论重离子对撞机（RHIC）。利用包含碰撞火球初始形状和方向的逐事件波动的初始条件和最近从偏心率标度、p_T积分的带电强子椭圆流的测量中心依赖性中提取的夸克-胶子等离子体比剪切粘度的eta/s值，我们得到了所有碰撞中心下π介子和质子的p_T谱和微分椭圆流v_2（p_T）的理论与实验的一致性。
