51 research outputs found
Relativistic Viscous Hydrodynamics for Multi-Component Systems with Multiple Conserved Currents
We would like to formulate relativistic dissipative hydrodynamics for
multi-component systems with multiple conserved currents. This is important for
analyses of the hot matter created in relativistic heavy ion collisions because
particle creations and annihilations of various particle species are frequently
taking place there. We show that consistent formulation in such systems
involves many non-trivialities, and derive constitutive equations that satisfy
Onsager reciprocal relations and describe the systems without ambiguity.Comment: 4 pages, no figures - To appear in the conference proceedings for Hot
Quarks 2010, June 21-26, La Londe-les-Maures, Franc
QCD equation of state with Tsallis statistics for heavy-ion collisions
Nonextensive statistics has attracted attention as a description of particle
spectra in nuclear collisions at QCD energies. First, we construct the equation
of state by incorporating Tsallis statistics based on the hadron resonance gas
and parton gas models. Thermodynamic conditions are found to impose constraints
on the -parameter of Tsallis distribution. Next, we apply the equation of
state to the relativistic hydrodynamic modeling of nuclear collisions. The
Cooper-Frye prescription is consistently modified. Numerical demonstrations
indicate that the model may describe charged particle spectra at Large Hadron
Collider in the transverse momentum range up to 6-8 GeV. Elliptic flow, on the
other hand, suggests a narrower range of applicability.Comment: 9 pages, 5 figures; revised version to appear in Physical Review
Microscopic analysis of the microscopic reversibility in quantum systems
We investigate the robustness of the microscopic reversibility in open
quantum systems which is discussed by Monnai [arXiv:1106.1982 (2011)]. We
derive an exact relation between the forward transition probability and the
reversed transition probability in the case of a general measurement basis. We
show that the microscopic reversibility acquires some corrections in general
and discuss the physical meaning of the corrections. Under certain processes,
some of the correction terms vanish and we numerically confirmed that the
remaining correction term becomes negligible; the microscopic reversibility
almost holds even when the local system cannot be regarded as macroscopic.Comment: 12 pages, 10 figure
Relaxation to equilibrium of expectation values in macroscopic quantum systems
A quantum mechanical explanation of the relaxation to equilibrium is shown
for macroscopic systems for nonintegrable cases and numerically verified. The
macroscopic system is initially in an equilibrium state, subsequently
externally perturbed during a finite time, and then isolated for a sufficiently
long time. We show a quantitative explanation that the initial microcanonical
state typically reaches to a state whose expectation values are
well-approximated by the average over another microcanonical ensemble.Comment: accepted to Physical Review
Diffusion in the Markovian limit of the spatio-temporal colored noise
We explore the diffusion process in the non-Markovian spatio-temporal
noise.%the escape rate problem in the non-Markovian spatio-temporal random
noise. There is a non-trivial short memory regime, i.e., the Markovian limit
characterized by a scaling relation between the spatial and temporal
correlation lengths. In this regime, a Fokker-Planck equation is derived by
expanding the trajectory around the systematic motion and the non-Markovian
nature amounts to the systematic reduction of the potential. For a system with
the potential barrier, this fact leads to the renormalization of both the
barrier height and collisional prefactor in the Kramers escape rate, with the
resultant rate showing a maximum at some scaling limit.Comment: 4pages,2figure
Centrality dependence of elliptic flow and QGP viscosity
In the Israel-Stewart's theory of second order hydrodynamics, we have
analysed the recent PHENIX data on charged particles elliptic flow in Au+Au
collisions.
PHENIX data demand more viscous fluid in peripheral collisions than in
central collisions. Over a broad range of collision centrality (0-10%- 50-60%),
viscosity to entropy ratio () varies between 0-0.17.Comment: Final version to be publiashed in J. Phys. G. 8 pages, 6 figures and
3 table
Relativistic dissipative hydrodynamics with extended matching conditions for ultra-relativistic heavy-ion collisions
Recently we proposed a novel approach to the formulation of relativistic
dissipative hydrodynamics by extending the so-called matching conditions in the
Eckart frame [Phys. Rev. {\bf C 85}, (2012) 14906]. We extend this formalism
further to the arbitrary Lorentz frame. We discuss the stability and causality
of solutions of fluid equations which are obtained by applying this formulation
to the Landau frame, which is more relevant to treat the fluid produced in
ultra-relativistic heavy-ion collisions. We derive equations of motion for a
relativistic dissipative fluid with zero baryon chemical potential and show
that linearized equations obtained from them are stable against small
perturbations. It is found that conditions for a fluid to be stable against
infinitesimal perturbations are equivalent to imposing restrictions that the
sound wave, , propagating in the fluid, must not exceed the speed of light
, i.e., . This conclusion is equivalent to that obtained in the
previous paper using the Eckart frame [Phys. Rev. {\bf C 85}, (2012) 14906].Comment: 2nd version. Typos corrected. 7 pages. Contribution to The European
Physical Journal A (Hadrons and Nuclei) topical issue about 'Relativistic
Hydro- and Thermodynamics in Nuclear Physics
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