106 research outputs found
Indications of early thermalization in relativistic heavy-ion collisions
The directed flow of particles emitted from the fireball created in a
heavy-ion collision is shown to be a very sensitive measure of the pressure
equilibration in the first 1 fm/c of the evolution. Performing a 3+1
dimensional relativistic hydrodynamic calculation with nonequilibrated
longitudinal and transverse pressures, we show that the directed flow is
strongly reduced if the pressure imbalance survives for even a short time.
Transverse momentum spectra, elliptic flow and interferometry correlation radii
are not very sensitive to this early pressure anisotropy. Comparison with the
data points toward a short equilibration time of the order of fm/c or
less
Short-range correlations in asymmetric nuclear matter
The spectral function of protons in the asymmetric nuclear matter is
calculated in the self-consistent T-matrix approach. The spectral function per
proton increases with increasing asymmetry. This effect and the density
dependence of the spectral function partially explain the observed increase of
the spectral function with the mass number of the target nuclei in electron
scattering experiments
Flow and interferometry in 3+1 dimensional viscous hydrodynamics
The expansion of the fireball created in Au-Au collisions at 200 GeV is
described in (3+1)-dimensional viscous hydrodynamics with shear and bulk
viscosities. We present results for the transverse momentum spectra, the
directed and elliptic flow and the interferometry radii.Comment: discussion of viscous corrections at freeze-out adde
Directed flow in ultrarelativistic heavy-ion collisions
We study the generation of directed flow in the hydrodynamic expansion of the
hot matter formed in ultrarelativistic heavy-ion collisions at 200GeV. The
experimentally observed negative directed flow in a wide range of central
pseudorapidities isreproduced assuming that the fireball is tilted away from
the collision axis. The tilt of the source is consistent with a preferential
emission in the forward/backward hemisphere from forward/backward participating
nucleons. The model reproduces the experimentally observed scaling of the
directed flow when going from Au-Au to Cu-Cu systems.Comment: figure adde
In medium T-matrix for nuclear matter with three-body forces - binding energy and single particle properties
We present spectral calculations of nuclear matter properties including
three-body forces. Within the in-medium T-matrix approach, implemented with the
CD-Bonn and Nijmegen potentials plus the three-nucleon Urbana interaction, we
compute the energy per particle in symmetric and neutron matter. The three-body
forces are included via an effective density dependent two-body force in the
in-medium T-matrix equations. After fine tuning the parameters of the
three-body force to reproduce the phenomenological saturation point in
symmetric nuclear matter, we calculate the incompressibility and the energy per
particle in neutron matter. We find a soft equation of state in symmetric
nuclear matter but a relatively large value of the symmetry energy. We study
the the influence of the three-body forces on the single-particle properties.
For symmetric matter the spectral function is broadened at all momenta and all
densities, while an opposite effect is found for the case of neutrons only.
Noticeable modification of the spectral functions are realized only for
densities above the saturation density. The modifications of the self-energy
and the effective mass are not very large and appear to be strongly suppressed
above the Fermi momentum.Comment: 20 pages, 11 figure
Dressed vertices
The response of a correlated nuclear system to an external field is
discussed. The Bethe-Salpeter equation for the dressed vertex is solved. The
kernel of the integral equation for the vertex is chosen consistently with the
approximation for the self-energy. This guarantees the fulfillment of the f-sum
rule for the response function
Collective flow in p-Pb and d-Pb collisions at TeV energies
We apply the hydrodynamic model for the dynamics of matter created in p-Pb
collisions at 4.4TeV and d-Pb collisions at 3.11TeV. The fluctuating initial
conditions are calculated in the Glauber Monte-Carlo model for several
centrality classes. The expansion is performed event by event in
3+1-dimensional viscous hydrodynamics. Noticeable elliptic and triangular flows
appear in the distributions of produced particles
In medium T matrix for neutron matter
We calculate the equation of state of pure neutron matter, comparing the
G-matrix calculation with the in-medium T-matrix result. At low densities, we
obtain similar energies per nucleon, however some differences appear at higher
densities. We use the self-consistent spectral functions from the T-matrix
approach to calculate the 1S0 superfluid gap including self-energy effects. We
find a reduction of the superfluid gap by 30%
Spectral properties of nuclear matter
We review self-consistent spectral methods for nuclear matter calculations.
The in-medium T-matrix approach is conserving and thermodynamically consistent.
It gives both the global and the single-particle properties the system. The
T-matrix approximation allows to address the pairing phenomenon in cold nuclear
matter. A generalization of nuclear matter calculations to the superfluid phase
is discussed and numerical results are presented for this case. The linear
response of a correlated system going beyond the
Hartree-Fock+Random-Phase-Approximation scheme is studied. The polarization is
obtained by solving a consistent Bethe-Salpeter equation for the coupling of
dressed nucleons to an external field. We find that multipair contributions are
important for the spin(isospin) response when the interaction is spin(isospin)
dependent.Comment: Talk given at the workshop "Progress in Nonequilibrium Green's
Functions III" 22-26 August 2005, Kie
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