11,815 research outputs found
Relativistic hydrodynamics in heavy-ion collisions: general aspects and recent developments
Relativistic hydrodynamics has been quite successful in explaining the
collective behaviour of the QCD matter produced in high energy heavy-ion
collisions at RHIC and LHC. We briefly review the latest developments in the
hydrodynamical modeling of relativistic heavy-ion collisions. Essential
ingredients of the model such as the hydrodynamic evolution equations,
dissipation, initial conditions, equation of state, and freeze-out process are
reviewed. We discuss observable quantities such as particle spectra and
anisotropic flow and effect of viscosity on these observables. Recent
developments such as event-by-event fluctuations, flow in small systems
(proton-proton and proton-nucleus collisions), flow in ultra central
collisions, longitudinal fluctuations and correlations and flow in intense
magnetic field are also discussed.Comment: 36 pages, 16 figures, invited review, published versio
Monte-Carlo statistical hadronization in relativistic heavy-ion collisions
A brief introduction to the statistical hadronization approach to particle
production in relativistic heavy-ion collisions is given. In the context of
fluid dynamics modeling various aspects of hadron emission at the freeze-out
are discussed. Practical applications of the presented concepts are presented
within the THERMINATOR Monte-Carlo hadron generator.Comment: Lectures delivered at the 53rd Karpacz Winter School of Theoretical
Physics, February 26th - March 4th, 2017, Karpacz, Poland ; Submitted to
Lect. Notes Phy
Double bracket dissipation in kinetic theory for particles with anisotropic interactions
We derive equations of motion for the dynamics of anisotropic particles
directly from the dissipative Vlasov kinetic equations, with the dissipation
given by the double bracket approach (Double Bracket Vlasov, or DBV). The
moments of the DBV equation lead to a nonlocal form of Darcy's law for the mass
density. Next, kinetic equations for particles with anisotropic interaction are
considered and also cast into the DBV form. The moment dynamics for these
double bracket kinetic equations is expressed as Lie-Darcy continuum equations
for densities of mass and orientation. We also show how to obtain a
Smoluchowski model from a cold plasma-like moment closure of DBV. Thus, the
double bracket kinetic framework serves as a unifying method for deriving
different types of dynamics, from density--orientation to Smoluchowski
equations. Extensions for more general physical systems are also discussed.Comment: 19 pages; no figures. Submitted to Proc. Roy. Soc.
Viscous Bianchi type I universes in brane cosmology
We consider the dynamics of a viscous cosmological fluid in the generalized
Randall-Sundrum model for an anisotropic, Bianchi type I brane. To describe the
dissipative effects we use the Israel-Hiscock-Stewart full causal thermodynamic
theory. By assuming that the matter on the brane obeys a linear barotropic
equation of state, and the bulk viscous pressure has a power law dependence on
the energy density, the general solution of the field equations can be obtained
in an exact parametric form. The obtained solutions describe generally a
non-inflationary brane world. In the large time limit the brane Universe
isotropizes, ending in an isotropic and homogeneous state. The evolution of the
temperature and of the comoving entropy of the Universe is also considered, and
it is shown that due to the viscous dissipative processes a large amount of
entropy is created in the early stages of evolution of the brane world.Comment: 13 pages, 5 figures, to appear in Class. Quantum Gra
Lumpy Structures in Self-Gravitating Disks
Following Toomre & Kalnajs (1991), local models of slightly dissipative
self-gravitating disks show how inhomogeneous structures can be maintained over
several galaxy rotations. Their basic physical ingredients are self-gravity,
dissipation and differential rotation. In order to explore the structures
resulting from these processes on the kpc scale, local simulation of
self-gravitating disks are performed in this paper in 2D as well as in 3D. The
third dimension becomes a priori important as soon as matter clumping causes a
tight coupling of the 3D equations of motion. The physically simple and general
framework of the model permits to make conclusions beyond the here considered
scales. A time dependent affine coordinate system is used, allowing to
calculate the gravitational forces via a particle-mesh FFT-method, increasing
the performance with respect to previous direct force calculations. Persistent
patterns, formed by transient structures, whose intensity and morphological
characteristic depend on the dissipation rate are obtained and described. Some
of our simulations reveal first signs of mass-size and velocity dispersion-size
power-law relations, but a clear scale invariant behavior will require more
powerful computer techniques.Comment: 28 pages, 32 figures. Accepted for publication in A&A. Full
resolution paper available at http://obswww.unige.ch/Preprints/dyn_art.htm
- …