2,329 research outputs found
Simple analytic solution of fireball hydrodynamics
A new family of simple analytic solutions of hydrodynamics is found for
non-relativistic, rotationally symmetric fireballs assuming an ideal gas
equation of state. The solution features linear flow profile and a non-trivial
transverse temperature profile. The radial temperature gradient vanishes only
in the collisionless gas limit. The Zimanyi-Bondorf-Garpman solution and the
Buda-Lund parameterization of expanding hydrodynamical sources are recovered as
special cases. The results are applied to predict new features of proton-proton
correlations and spectra data at 1.93 AGeV Ni + Ni reactions.Comment: Latex, Revte
Overview of charm production at RHIC
In this presentation, I discussed a) the charm total cross-section and its
comparisons to measurements at other beam energies and pQCD calculations; b)
the semileptonic decay of charmed hadrons and the sensitivity of non-photonic
leptons to charm quark collective flow and freeze-out; c) semileptonic decayed
electron spectrum at high transverse momentum, its comparison to FONLL in p+p
and d+Au collisions, and heavy-quark energy loss in Au+Au collisions.Comment: 8 pages, 4 figures, overview talk at SQM2006: Strangeness in Quark
Matter Los Angeles, CA, Mar. 26-31, 2006; minor text changes and references
adde
Flow fluctuations and long-range correlations: elliptic flow and beyond
These proceedings consist of a brief overview of the current understanding of
collective behavior in relativistic heavy-ion collisions. In particular, recent
progress in understanding the implications of event-by-event fluctuations have
solved important puzzles in existing data -- the "ridge" and "shoulder"
phenomena of long-range two-particle correlations -- and have created an
exciting opportunity to tightly constrain theoretical models with many new
observables.Comment: 10 pages, 2 figures, Proceedings for the 22nd International
Conference On Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter
2011), Annecy, France, May 23 - 28, 2011; includes Fig. 2 which was omitted
from journal submission for lack of spac
Boundary and expansion effects on two-pion correlation functions in relativistic heavy-ion collisions
We examine the effects that a confining boundary together with hydrodynamical
expansion play on two-pion distributions in relativistic heavy-ion collisions.
We show that the effects arise from the introduction of further correlations
due both to collective motion and the system's finite size. As is well known,
the former leads to a reduction in the apparent source radius with increasing
average pair momentum K. However, for small K, the presence of the boundary
leads to a decrease of the apparent source radius with decreasing K. These two
competing effects produce a maximum for the effective source radius as a
function of K.Comment: 6 pages, 5 Eps figures, uses RevTeX and epsfi
Elliptic flow at large transverse momenta from quark coalescence
We show that hadronization via quark coalescence enhances hadron elliptic
flow at large pT relative to that of partons at the same transverse momentum.
Therefore, compared to earlier results based on covariant parton transport
theory, more moderate initial parton densities dN/d\eta(b=0) ~ 1500-3000 can
explain the differential elliptic flow v_2(pT) data for Au+Au reactions at
s^1/2=130 and 200 AGeV from RHIC. In addition, v2(pT) could saturate at about
50% higher values for baryons than for mesons. If strange quarks have weaker
flow than light quarks, hadron v_2 at high pT decreases with relative
strangeness content.Comment: Minor changes, extended discussion. To appear in PR
Evidence of early multi-strange hadron freeze-out in high energy nuclear collisions
Recently reported transverse momentum distributions of strange hadrons
produced in Pb(158AGeV) on Pb collisions and corresponding results from the
relativistic quantum molecular dynamics (RQMD) approach are examined. We argue
that the experimental observations favor a scenario in which multi-strange
hadrons are formed and decouple from the system rather early at large energy
densities (around 1 GeV/fm). The systematics of the strange and non-strange
particle spectra indicate that the observed transverse flow develops mainly in
the late hadronic stages of these reactions.Comment: 4 pages, 4 figure
Effect of Finite Granularity of Detectors on Anisotropy Coefficients
The coefficients that describe the anisotropy in the azimuthal distribution
of particles are lower when the particles are recorded in a detector with
finite granularity and measures only hits. This arises due to loss of
information because of multiple hits in any channel. The magnitude of this loss
of signal depends both on the occupancy and on the value of the coefficient.
These correction factors are obtained for analysis methods differing in detail,
and are found to be different.Comment: 11 pages including 2 figure
Quantum-Statistical Correlations and Single Particle Distributions for Slowly Expanding Systems with Temperature Profile
Competition among particle evaporation, temperature gradient and flow is
investigated in a phenomenological manner, based on a simultaneous analysis of
quantum statistical correlations and momentum distributions for a
non-relativistic, spherically symmetric, three-dimensionally expanding, finite
source. The parameters of the model emission function are constrained by fits
to neutron and proton momentum distributions and correlation functions in
intermediate energy heavy-ion collisions. The temperature gradient is related
to the momentum dependence of the radius parameters of the two-particle
correlation function, as well as to the momentum-dependent temperature
parameter of the single particle spectrum, while a long duration of particle
evaporation is found to be responsible for the low relative momentum behavior
of the two-particle correlations.Comment: 20 pages + 5 ps figures, ReVTeX, uses psfig.sty, the description is
extended to include final state interactions, phenomenological evaporation
and to fit intermediate energy heavy ion proton and neutron spectrum and
correlation dat
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