Generalized Entropy and Transport Coefficients of Hadronic Matter

We use the generalized entropy four-current of the Muller-Israel-Stewart (MIS) theory of relativistic dissipative fluids to obtain information about fluctuations around equilibrium. This allows one to compute the non-classical coefficients of the entropy 4-flux in terms of the equilibrium distribution functions. The Green-Kubo formulae are used to compute the classical or standard transport coefficients from the fluctuations of entropy due to dissipative fluxes.Comment: 8 pages, Zimanyi 75 Memorial Workshop on Hadronic and Quark Matter, Budapest, Hungary, 200

Dissipative Relativistic Fluid Dynamics for Nuclear Collisions

In the context of the M\"uller-Israel-Stewart second-order theory for dissipative fluids due to Grad, we analyze the effects of thermal conduction and viscosity in heavy ion collisions. We contrast the results to those of the first-order theory due to Eckart and to Landau and Lifshitz and to those of perfect (ideal) fluid due to Euler. We study the energy density and entropy density evolution of a pion gas produced in the heavy ion collisions. The truncated version of the second-order theory is used to find the dissipative quantities.Comment: 10 pages, 4 figures, Proceedings of the 17th Winter Workshop on Nuclear Dynamics, Park City, Utah, March 10-17, 200

Viscous hydrodynamics

We study the role of viscosity in the early stages of relativistic heavy ion collisions. We investigate the role of viscosity on the chemical equilibration of a parton gas. In the presence of viscosity the lifetime of the system is increased. The temperature as well as the parton fugacities evolve more slowly compared to the ideal fluid dynamics.Comment: 4 pages, Strange Quark Matter 2004, Cape Town, South Afric

Equation of State and Transport Coefficients of Relativistic Nuclear Matter

In order to evaluate qualitatively the space-time evolution of hot and dense nuclear matter the underlying equation of state and transport coefficients must be known. In this study a specific equation of state is studied: the pion gas. The classical or standard transport coefficients, namely the bulk viscosity, shear viscsoity and thermal conductivity are devided by the relaxation times for the corresponding dissipative fluxes and then studied as functions of mass to temperature ratio.Comment: 5 pages, Strange Quark Matter 2007, Levoca, Slovaki

Relativistic Dynamics of Non-ideal Fluids: Viscous and heat-conducting fluids I. General Aspects and 3+1 Formulation for Nuclear Collisions

Relativistic non-ideal fluid dynamics is formulated in 3+1 space--time dimensions. The equations governing dissipative relativistic hydrodynamics are given in terms of the time and the 3-space quantities which correspond to those familiar from non-relativistic physics. Dissipation is accounted for by applying the causal theory of relativistic dissipative fluid dynamics. As a special case we consider a fluid without viscous/heat couplings in the causal system of transport/relaxation equations. For the study of physical systems we consider pure (1+1)-dimensional expansion in planar geometry, (1+1)-dimensional spherically symmetric ({\em fireball}) expansion, (1+1)-dimensional cylindrically symmetric expansion and a (2+1)-dimensional expansion with cylindrical symmetry in the transverse plane ({\em firebarell} expansion). The transport/relaxation equations are given in terms of the spatial components of the dissipative fluxes, since these are not independent. The choice for the independent components is analogous to the non-relativistic equations.Comment: 49 pages, added references, typos adde

A relativistic dissipative hydrodynamic description for systems including particle number changing processes

Relativistic dissipative hydrodynamic equations are extended by taking into account particle number changing processes in a gluon system, which expands in one dimension boost-invariantly. Chemical equilibration is treated by a rate equation for the particle number density based on Boltzmann equation and Grad's ansatz for the off-equilibrium particle phase space distribution. We find that not only the particle production, but also the temperature and the momentum spectra of the gluon system, obtained from the hydrodynamic calculations, are sensitive to the rates of particle number changing processes. Comparisons of the hydrodynamic calculations with the transport ones employing the parton cascade BAMPS show the inaccuracy of the rate equation at large shear viscosity to entropy density ratio. To improve the rate equation, the Grad's ansatz has to be modified beyond the second moments in momentum.Comment: 20 pages, 11 figure