351 research outputs found
Longitudinal broadening of near side jets due to parton cascade
Longitudinal broadening along direction on near side in
two-dimensional () di-hadron correlation
distribution has been studied for central Au+Au collisions at =
200 GeV, within a dynamical multi-phase transport model. It was found that the
longitudinal broadening is generated by a longitudinal flow induced by strong
parton cascade in central Au+Au collisions, in comparison with p+p collisions
at = 200 GeV. The longitudinal broadening may shed light on the
information about strongly interacting partonic matter at RHIC.Comment: 5 pages, 4 figures; accepted by Eur. Phys. J.
Magnetic resonance imaging of glutamate in neuroinflammation
AbstractInflammation in central nervous system (CNS) is one of the most severe diseases, and also plays an impellent role in some neurodegenerative diseases. Glutamate (Glu) has been considered relevant to the pathogenesis of neuroinflammation. In order to diagnose neuroinflammation incipiently and precisely, we review the pathobiological events in the early stages of neuroinflammation, the interactions between Glu and neuroinflammation, and two kinds of magnetic resonance techniques of imaging Glu (chemical exchange saturation transfer and magnetic resonance spectroscopy)
Partonic effects on the elliptic flow at relativistic heavy ion collisions
The elliptic flow in heavy ion collisions at RHIC is studied in a multiphase
transport model. By converting the strings in the high energy density regions
into partons, we find that the final elliptic flow is sensitive to the parton
scattering cross section. To reproduce the large elliptic flow observed in
Au+Au collisions at GeV requires a parton scattering cross
section of about 6 mb. We also study the dependence of the elliptic flow on the
particle multiplicity, transverse momentum, and particle mass.Comment: 7 pages, 7 figures, revtex, text added to detail the procedure for
conversions between hadrons and parton
Baryon Number Fluctuation and the Quark-Gluon Plasma
We show that or , the squared baryon or
antibaryon number fluctuation per baryon or antibaryon, is a possible signature
for the quark-gluon plasma that is expected to be created in relativistic heavy
ion collisions, as it is a factor of three smaller than in an equilibrated
hadronic matter due to the fractional baryon number of quarks. Using kinetic
equations with exact baryon number conservation, we find that their values in
an equilibrated matter are half of those expected from a Poisson distribution.
Effects due to finite acceptance and non-zero net baryon number are also
studied.Comment: discussion and references added, version to appear in PR
Recent results from parton cascade and microscopic transport
Parton cascade is a microscopic transport approach for the study of the
space-time evolution of the Quark-Gluon Plasma produced in relativistic heavy
ion collisions and its experimental manifestations. In the following, parton
cascade calculations on elliptic flow and thermalization will be discussed.
Dynamical evolution is shown to be important for the production of elliptic
flow including the scaling and the breaking of the scaling of elliptic flow.
The degree of thermalization is estimated using both an elastic parton cascade
and a radiative transport model. A longitudinal to transverse pressure ratio,
, is shown to be expected in the central cell in central
collisions. This provides information on viscous corrections to the ideal
hydrodynamical approach.Comment: Presented at Hot Quarks 2008, Estes Park, Colorado, USA, 18-23 August
200
J/psi couplings to charmed resonances and to pi
We present an evaluation of the strong couplings JD^(*)D^(*) and
JD^(*)D^(*)pi by an effective field theory of quarks and mesons. These
couplings are necessary to calculate pi+J/psi --> D^(*)+barD^(*) cross
sections, an important background to the J/psi suppression signal in the
quark-gluon plasma. We write down the general effective lagrangian and compute
the relevant couplings in the soft pion limit and beyond.Comment: 11 pages, 4 figures, 2 reference added and minor comments, style
changed to RevTe
Search for Small Trans-Neptunian Objects by the TAOS Project
The Taiwan-America Occultation Survey (TAOS) aims to determine the number of
small icy bodies in the outer reach of the Solar System by means of stellar
occultation. An array of 4 robotic small (D=0.5 m), wide-field (f/1.9)
telescopes have been installed at Lulin Observatory in Taiwan to simultaneously
monitor some thousand of stars for such rare occultation events. Because a
typical occultation event by a TNO a few km across will last for only a
fraction of a second, fast photometry is necessary. A special CCD readout
scheme has been devised to allow for stellar photometry taken a few times per
second. Effective analysis pipelines have been developed to process stellar
light curves and to correlate any possible flux changes among all telescopes. A
few billion photometric measurements have been collected since the routine
survey began in early 2005. Our preliminary result of a very low detection rate
suggests a deficit of small TNOs down to a few km size, consistent with the
extrapolation of some recent studies of larger (30--100 km) TNOs.Comment: 4 pages, 3 figures, IAU Symposium 23
The Ter-Mikayelian Effect on QCD Radiative Energy Loss
The color dielectric modification of the gluon dispersion relation in a dense
QCD medium suppresses both the soft and collinear gluon radiation associated
with jet production. We compute both the longitudinal and transverse plasmon
contributions to the zeroth order in opacity radiative energy loss. This QCD
analog of the Ter-Mikayelian effect in QED leads to reduction of the
energy loss of high transverse momentum charm quarks produced in a QCD plasma
with a characteristic Debye mass GeV.Comment: 18 Pages, 16 Figure
Mesoscale magnetism at the grain boundaries in colossal magnetoresistive films
We report the discovery of mesoscale regions with distinctive magnetic
properties in epitaxial LaSrMnO films which exhibit
tunneling-like magnetoresistance across grain boundaries. By using
temperature-dependent magnetic force microscopy we observe that the mesoscale
regions are formed near the grain boundaries and have a different Curie
temperature (up to 20 K {\it higher}) than the grain interiors. Our images
provide direct evidence for previous speculations that the grain boundaries in
thin films are not magnetically and electronically sharp interfaces. The size
of the mesoscale regions varies with temperature and nature of the underlying
defect.Comment: 4 pages of text, 4 figure
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