5,400 research outputs found
Elliptic flow of resonances at RHIC: probing final state interactions and the structure of resonances
We propose the measurement of the elliptic flow of hadron resonances at the
Relativistic Heavy Ion Collider as a tool to probe the amount of hadronic final
state interactions for resonances at intermediate and large transverse momenta.
This can be achieved by looking at systematic deviations of the measured flow
coefficient from the scaling law given by the quark recombination
formalism. Our method can be generalized to explore the structure of exotic
particles, such as the recently found pentaquark .Comment: 5 pages, 2 figures; v2: accepted version for publication in Physical
Review C rapid communication
Hadronization in heavy ion collisions: Recombination and fragmentation of partons
We argue that the emission of hadrons with transverse momentum up to about 5
GeV/c in central relativistic heavy ion collisions is dominated by
recombination, rather than fragmentation of partons. This mechanism provides a
natural explanation for the observed constant baryon-to-meson ratio of about
one and the apparent lack of a nuclear suppression of the baryon yield in this
momentum range. Fragmentation becomes dominant at higher transverse momentum,
but the transition point is delayed by the energy loss of fast partons in dense
matter.Comment: 4 pages, 2 figures; v2: reference [8] added; v3: Eq.(2) corrected,
two references added, version to appear in PR
MAESTRO, CASTRO, and SEDONA -- Petascale Codes for Astrophysical Applications
Performing high-resolution, high-fidelity, three-dimensional simulations of
Type Ia supernovae (SNe Ia) requires not only algorithms that accurately
represent the correct physics, but also codes that effectively harness the
resources of the most powerful supercomputers. We are developing a suite of
codes that provide the capability to perform end-to-end simulations of SNe Ia,
from the early convective phase leading up to ignition to the explosion phase
in which deflagration/detonation waves explode the star to the computation of
the light curves resulting from the explosion. In this paper we discuss these
codes with an emphasis on the techniques needed to scale them to petascale
architectures. We also demonstrate our ability to map data from a low Mach
number formulation to a compressible solver.Comment: submitted to the Proceedings of the SciDAC 2010 meetin
Resonance Production in RHIC Collisions
Results of resonance particle production measured at RHIC in 200 GeV Au+Au collisions are compared to measurements in p+p and d+Au
collisions in order to verify the existence of an extended hardronically
interacting medium. Yield and momentum distributions of resonances maybe
modified during the fireball lifetime due to resonance decay and the subsequent
rescattering of their decay daughters as well as the regeneration of resonances
from their decay products. Modified momentum spectra in heavy ion collisions
may change the nuclear modification factor R. The influence on the
elliptic flow v due to late regeneration of resonances is discussed.Comment: 6 pages, 6 figures, Proceedings of the 22st Winter Workshop on
Nuclear Dynamics, San Diago, California, 12-18 March, 200
QCD matter within a quasi-particle model and the critical end point
We compare our quasi-particle model with recent lattice QCD results for the
equation of state at finite temperature and baryo-chemical potential. The
inclusion of the QCD critical end point into models is discussed. We propose a
family of equations of state to be employed in hydrodynamical calculations of
particle spectra at RHIC energies and compare with the differential azimuthal
anisotropy of strange and charm hadrons.Comment: talk at Quark Matter 2005, August 4 - 9, 2005, Budapest, Hungar
Charge-dependent anisotropic flow in high-energy heavy-ion collisions from relativistic resistive magneto-hydrodynamic expansion
We have investigated the charge-dependent anisotropic flow in high-energy
heavy-ion collisions, using relativistic resistive magneto-hydrodynamics
(RRMHD). We consider the optical Glauber model as an initial model of the
quark-gluon plasma (QGP) and the solution of the Maxwell equations with source
term of the charged particles in two colliding nuclei as initial
electromagnetic fields. The RRMHD simulation is performed with these initial
conditions in Au-Au and Cu-Au collisions at GeV.
We have calculated the charge-odd contribution to the directed flow and elliptic flow in both collisions based on electric charge
distributions as a consequence of RRMHD. Our results show that the
and are approximately proportional to the electrical conductivity
() of the medium. In the case, our
result of is consistent with STAR data in Au-Au collisions.
Furthermore, in Cu-Au collisions, has a non-zero value at . We conclude that the charge-dependent anisotropic flow is a good probe to
extract the electrical conductivity of the QGP medium in high-energy heavy-ion
experiments.Comment: 10 pages, 9 figure
Relativistic resistive magneto-hydrodynamics code for high-energy heavy-ion collisions
We construct a relativistic resistive magneto-hydrodynamic (RRMHD) numerical
simulation code for high-energy heavy-ion collisions. We split the system of
differential equations into two parts, a non-stiff and a stiff part. For the
non-stiff part, we evaluate the numerical flux using HLL approximated Riemann
solver and execute the time integration by the second-order of Runge-Kutta
algorithm. For the stiff part, which appears in Ampere's law, we integrate the
equations using semi-analytic solutions of the electric field. We employ the
generalized Lagrange multiplier method to ensure the divergence-free constraint
for the magnetic field and Gauss's law. We confirm that our code reproduces
well the results of standard RRMHD tests in the Cartesian coordinates. In the
Milne coordinates, the code with high conductivity is validated against
relativistic ideal MHD tests. We also verify the semi-analytic solutions of the
accelerating longitudinal expansion of relativistic resistive
magneto-hydrodynamics in high-energy heavy-ion collisions in a comparison with
our numerical result. Our numerical code reproduces these solutions.Comment: 16 pages, 14 figure
Space-time evolution of bulk QCD matter
We introduce a combined fully three-dimensional macroscopic/microscopic
transport approach employing relativistic 3D-hydrodynamics for the early,
dense, deconfined stage of the reaction and a microscopic non-equilibrium model
for the later hadronic stage where the equilibrium assumptions are not valid
anymore. Within this approach we study the dynamics of hot, bulk QCD matter,
which is being created in ultra-relativistic heavy ion collisions at RHIC. Our
approach is capable of self-consistently calculating the freezeout of the
hadronic system, while accounting for the collective flow on the hadronization
hypersurface generated by the QGP expansion. In particular, we perform a
detailed analysis of the reaction dynamics, hadronic freezeout, and transverse
flow.Comment: 24 pages, 27 figure
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