14 research outputs found
Relativistic BGK hydrodynamics
Bhatnagar-Gross-Krook (BGK) collision kernel is employed in the Boltzmann
equation to formulate relativistic dissipative hydrodynamics. In this
formulation, we find that there remains freedom of choosing a matching
condition that affects the scalar transport in the system. We also propose a
new collision kernel which, unlike BGK collision kernel, is valid in the limit
of zero chemical potential and derive relativistic first-order dissipative
hydrodynamics using it. We study the effects of this new formulation on the
coefficient of bulk viscosity.Comment: 9 pages, 4 figure
Relaxation-time approximation with pair production and annihilation processes
We extend the Boltzmann equation in the relaxation-time approximation to explicitly include transitions between particles forming an interacting mixture. Using the detailed balance condition as well as conditions of energy-momentum and current conservation, we show that only two independent relaxation time scales are allowed in such an interacting system. Dissipative hydrodynamic equations and the form of transport coefficients are subsequently derived for this case. We find that the shear and bulk viscosity coefficients, as well as the baryon charge conductivity, are independent of the transition time scale. However, the bulk viscosity and conductivity coefficients that can be attributed to the individual components of the mixture depend on the transition time
New Developments in Relativistic Fluid Dynamics with spin
In this work, we briefly review the progress made in the formulation of
hydrodynamics with spin with emphasis on the application to the relativistic
heavy-ion collisions. In particular, we discuss the formulation of
hydrodynamics with spin for perfect-fluid and the first order viscous
corrections with some discussion on the calculation of spin kinetic
coefficients. Finally, we apply relativistic hydrodynamics with spin to the
relativistic heavy-ion collisions to calculate the spin polarization of
-particles.Comment: 30 pages, 6 figures, Invited mini revie
Dissipative Spin Dynamics in Relativistic Matter
Using classical description of spin degrees of freedom, we extend recent
formulation of the perfect-fluid hydrodynamics for spin-polarized fluids to the
case including dissipation. Our work is based on the analysis of classical
kinetic equations for massive particles with spin-1/2, with the collision terms
treated in the relaxation time approximation. The kinetic-theory framework
determines the structure of viscous and diffusive terms and allows to
explicitly calculate a complete set of new kinetic coefficients that
characterize dissipative spin dynamics.Comment: 27 page
Relativistic spin-magnetohydrodynamics
Starting from kinetic theory description of massive spin-1/2 particles in
presence of magnetic field, equations for relativistic dissipative
non-resistive magnetohydrodynamics are obtained in the small polarization
limit. We use a relaxation time approximation for the collision kernel in the
relativistic Boltzmann equation and calculate non-equilibrium corrections to
the phase-space distribution function of spin-polarizable particles. We obtain
multiple novel transport coefficients and show that all dissipative currents
contain coupling between spin and magnetic field at first-order in gradients.Comment: 7 page
Polarization of spin-1/2 particles with effective spacetime dependent masses
Semiclassical expansion of the Wigner function for spin-1/2 fermions having
an effective spacetime-dependent mass is used to analyze spin-polarization
effects. The existing framework is reformulated to obtain a differential
equation directly connecting the particle spin tensor with the effective mass.
It reflects the conservation of the total angular momentum in a system. In
general, we find that the gradients of mass act as a source of the spin
polarization, although this effect is absent for simple boost-invariant
dynamics.Comment: 5 pages, 2 figures, comments are welcom
Relativistic dissipative spin dynamics in the relaxation time approximation
The concept of the Wigner function is used to construct a semi-classical kinetic theory describing the evolution of the axial current phase-space density of spin- particles in the relaxation time approximation. The resulting approach can be used to study spin polarization effects in relativistic matter, in particular, in heavy-ion collisions. An expression for the axial current based on the classical treatment of spin is also introduced and we show that it is consistent with earlier calculations using Wigner functions. Finally, we derive non-equilibrium corrections to the spin tensor, which are used to define, for the first time, the structure of spin transport coefficients in relativistic matter