8,773 research outputs found
High Azimuthal Asymmetry in Non-central A+A at RHIC
The high GeV azimuthal asymmetry, , in
non-central nuclear collisions at RHIC is shown to be a sensitive measure of
the initial parton density distribution of the produced quark-gluon plasma. A
generalization of the Gyulassy-Levai-Vitev (GLV) non-abelian energy loss
formalism including Bjorken 1+1D expansion as well as important kinematic
constraints is used.Comment: 4 pages, Revtex, bbox.sty, 4 eps figures, references added, minor
corrections, Phys.Rev.Lett versio
Centrality and pseudorapidity dependence of charged hadron production at intermediate pT in Au+Au collisions at sqrt[sNN ]=130 GeV
We present STAR measurements of charged hadron production as a function of centrality in Au+Au collisions at sqrt[sNN ]=130 GeV . The measurements cover a phase space region of 0.2 pcutT , and studied the results in the framework of participant and binary scaling. No clear evidence is observed for participant scaling of charged hadron yield in the measured pT region. The relative importance of hard scattering processes is investigated through binary scaling fraction of particle production
The non-Abelian feature of parton energy loss in energy dependence of jet quenching in high-energy heavy-ion collisions
One of the non-Abelian features of parton energy loss is the ratio between gluon and quark jets. Since jet production rate is
dominated by quark jets at high and by gluon jets at low
, high hadron suppression in high-energy heavy-ion collisions should
reflect such a non-Abelian feature. Within a leading order perturbative QCD
parton model that incorporates transverse expansion and Woods-Saxon nuclear
distribution, the energy dependence of large GeV/ hadron
suppression is found to be sensitive to the non-Abelian feasture of parton
energy loss and could be tested by data from low energy runs at RHIC or data
from LHC.Comment: RevTex 4, 7 pages, 3 figure
Precise Coulomb wave functions for a wide range of complex l, eta and z
A new algorithm to calculate Coulomb wave functions with all of its arguments
complex is proposed. For that purpose, standard methods such as continued
fractions and power/asymptotic series are combined with direct integrations of
the Schrodinger equation in order to provide very stable calculations, even for
large values of |eta| or |Im(l)|. Moreover, a simple analytic continuation for
Re(z) < 0 is introduced, so that this zone of the complex z-plane does not pose
any problem. This code is particularly well suited for low-energy calculations
and the calculation of resonances with extremely small widths. Numerical
instabilities appear, however, when both |eta| and |Im(l)| are large and
|Re(l)| comparable or smaller than |Im(l)|
Sensitivities of the Proton-Nucleus Elastical Scattering Observables of 6He and 8He at Intermediate Energies
We investigate the use of proton-nucleus elastic scattering experiments using
secondary beams of 6He and 8He to determine the physical structure of these
nuclei. The sensitivity of these experiments to nuclear structure is examined
by using four different nuclear structure models with different spatial
features using a full-folding optical potential model. The results show that
elastic scattering at intermediate energies (<100 MeV per nucleon) is not a
good constraint to be used to determine features of structure. Therefore
researchers should look elsewhere to put constraints on the ground state wave
function of the 6He and 8He nuclei.Comment: To be published in Phys. Rev.
Nucleon-nucleus scattering as a test of shell structure of some light mass exotic nuclei
Shell model wave functions have been used to form microscopic g-folding
optical potentials with which elastic scattering data from 8He, 10,11C, and
18,20,22O scattering on hydrogen has been analyzed. Those potentials, the
effective two-nucleon interaction used in their formation, and the shell model
details, then have been used in distorted wave approximation calculations of
differential cross sections from inelastic scattering to the first excited
states of five of those radioactive ions.Comment: 13 pages, 7 figure
Off-center collisions in AdS_5 with applications to multiplicity estimates in heavy-ion collisions
We study the trapped surface produced by an off-center collision of
light-like, point-sourced shock waves in anti-de Sitter space. We find an
analytic expression for the shape of the trapped surface in the limit where the
energy of the shock waves is large and the impact parameter is not too large.
We use the area of the trapped surface to estimate a lower bound on the entropy
produced in the collision. We compare our results to particle multiplicity
measurements in heavy-ion collisions as interpreted through the Glauber model.
In an attempt to roughly simulate the effects of asymptotic freedom and
confinement in quantum chromodynamics, we also consider the effects of slicing
off parts of anti-de Sitter space.Comment: 43 pages, 12 figures, 2 appendice
Effective-Mass Dirac Equation for Woods-Saxon Potential: Scattering, Bound States and Resonances
Approximate scattering and bound state solutions of the one-dimensional
effective-mass Dirac equation with the Woods-Saxon potential are obtained in
terms of the hypergeometric-type functions. Transmission and reflection
coefficients are calculated by using behavior of the wave functions at
infinity. The same analysis is done for the constant mass case. It is also
pointed out that our results are in agreement with those obtained in
literature. Meanwhile, an analytic expression is obtained for the transmission
resonance and observed that the expressions for bound states and resonances are
equal for the energy values .Comment: 20 pages, 6 figure
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